Radar - Knowledge

2633:. There is an appealing intuitive interpretation of this relationship in a radar. Matched filtering allows the entire energy received from a target to be compressed into a single bin (be it a range, Doppler, elevation, or azimuth bin). On the surface it appears that then within a fixed interval of time, perfect, error free, detection could be obtained. This is done by compressing all energy into an infinitesimal time slice. What limits this approach in the real world is that, while time is arbitrarily divisible, current is not. The quantum of electrical energy is an electron, and so the best that can be done is to match filter all energy into a single electron. Since the electron is moving at a certain temperature ( 457: 61: 883: 774: 3434: 4133:, require liquid coolant. The electron beam must contain 5 to 10 times more power than the microwave output, which can produce enough heat to generate plasma. This plasma flows from the collector toward the cathode. The same magnetic focusing that guides the electron beam forces the plasma into the path of the electron beam but flowing in the opposite direction. This introduces FM modulation which degrades Doppler performance. To prevent this, liquid coolant with minimum pressure and flow rate is required, and deionized water is normally used in most high power surface radar systems that use Doppler processing. 3536: 2789:(PPI) radar with a rotating antenna, this will usually be seen as a "sun" or "sunburst" in the center of the display as the receiver responds to echoes from dust particles and misguided RF in the waveguide. Adjusting the timing between when the transmitter sends a pulse and when the receiver stage is enabled will generally reduce the sunburst without affecting the accuracy of the range since most sunburst is caused by a diffused transmit pulse reflected before it leaves the antenna. Clutter is considered a passive interference source since it only appears in response to radar signals sent by the radar. 683: 45: 2989:

detect. This could be offset by using more pulses, but this would shorten the maximum range. So each radar uses a particular type of signal. Long-range radars tend to use long pulses with long delays between them, and short range radars use smaller pulses with less time between them. As electronics have improved many radars now can change their pulse repetition frequency, thereby changing their range. The newest radars fire two pulses during one cell, one for short range (about 10 km (6.2 mi)) and a separate signal for longer ranges (about 100 km (62 mi)).

2849:(AGC), is a method that relies on clutter returns far outnumbering echoes from targets of interest. The receiver's gain is automatically adjusted to maintain a constant level of overall visible clutter. While this does not help detect targets masked by stronger surrounding clutter, it does help to distinguish strong target sources. In the past, radar AGC was electronically controlled and affected the gain of the entire radar receiver. As radars evolved, AGC became computer-software-controlled and affected the gain with greater granularity in specific detection cells. 2704: 1614: 3505:

target location in three dimensions. Most 2D surveillance radars use a spoiled parabolic antenna with a narrow azimuthal beamwidth and wide vertical beamwidth. This beam configuration allows the radar operator to detect an aircraft at a specific azimuth but at an indeterminate height. Conversely, so-called "nodder" height finding radars use a dish with a narrow vertical beamwidth and wide azimuthal beamwidth to detect an aircraft at a specific height but with low azimuthal precision.

3221:" capability required to improve military air combat survivability. Pulse-Doppler is also used for ground based surveillance radar required to defend personnel and vehicles. Pulse-doppler signal processing increases the maximum detection distance using less radiation close to aircraft pilots, shipboard personnel, infantry, and artillery. Reflections from terrain, water, and weather produce signals much larger than aircraft and missiles, which allows fast moving vehicles to hide using 3559: 2985:, accurate distance measurement requires high-speed electronics. In most cases, the receiver does not detect the return while the signal is being transmitted. Through the use of a duplexer, the radar switches between transmitting and receiving at a predetermined rate. A similar effect imposes a maximum range as well. In order to maximize range, longer times between pulses should be used, referred to as a pulse repetition time, or its reciprocal, pulse repetition frequency. 3176: 3009: 3023:

broadcasting at the time the reflected signal arrives back at the radar. By comparing the frequency of the two signals the difference can be easily measured. This is easily accomplished with very high accuracy even in 1940s electronics. A further advantage is that the radar can operate effectively at relatively low frequencies. This was important in the early development of this type when high-frequency signal generation was difficult or expensive.

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instead of broadcasting and receiving from an aimed antenna, CH broadcast a signal floodlighting the entire area in front of it, and then used one of Watson-Watt's own radio direction finders to determine the direction of the returned echoes. This fact meant CH transmitters had to be much more powerful and have better antennas than competing systems but allowed its rapid introduction using existing technologies.

586: 2868:). This clutter type is especially bothersome since it appears to move and behave like other normal (point) targets of interest. In a typical scenario, an aircraft echo is reflected from the ground below, appearing to the receiver as an identical target below the correct one. The radar may try to unify the targets, reporting the target at an incorrect height, or eliminating it on the basis of 5868: 2966: 3095:

kilowatts. On reception, the signal is sent into a system that delays different frequencies by different times. The resulting output is a much shorter pulse that is suitable for accurate distance measurement, while also compressing the received energy into a much higher energy peak and thus reducing the signal-to-noise ratio. The technique is largely universal on modern large radars.

4021:, subdivided as below. Oxygen in the air is an extremely effective attenuator around 60 GHz, as are other molecules at other frequencies, leading to the so-called propagation window at 94 GHz. Even in this window the attenuation is higher than that due to water at 22.2 GHz. This makes these frequencies generally useful only for short-range highly specific radars, like 3472: 4316: 622: 971:, are too strongly attenuated. Weather phenomena, such as fog, clouds, rain, falling snow, and sleet, that block visible light are usually transparent to radio waves. Certain radio frequencies that are absorbed or scattered by water vapour, raindrops, or atmospheric gases (especially oxygen) are avoided when designing radars, except when their detection is intended. 2981:: transmit a short pulse of radio signal (electromagnetic radiation) and measure the time it takes for the reflection to return. The distance is one-half the round trip time multiplied by the speed of the signal. The factor of one-half comes from the fact that the signal has to travel to the object and back again. Since radio waves travel at the 2695:(SNR). SNR is defined as the ratio of the signal power to the noise power within the desired signal; it compares the level of a desired target signal to the level of background noise (atmospheric noise and noise generated within the receiver). The higher a system's SNR the better it is at discriminating actual targets from noise signals. 3704:'s effective aperture figure means that for any given antenna (or reflector) size will be more efficient at longer wavelengths. Additionally, shorter wavelengths may interact with molecules or raindrops in the air, scattering the signal. Very long wavelengths also have additional diffraction effects that make them suitable for 3134:, military radar). The Doppler effect is only able to determine the relative speed of the target along the line of sight from the radar to the target. Any component of target velocity perpendicular to the line of sight cannot be determined by using the Doppler effect alone, but it can be determined by tracking the target's 3214:. Coherency requirements are not as strict as those for military systems because individual signals ordinarily do not need to be separated. Less sophisticated filtering is required, and range ambiguity processing is not normally needed with weather radar in comparison with military radar intended to track air vehicles. 3549:

Applied similarly to the parabolic reflector, the slotted waveguide is moved mechanically to scan and is particularly suitable for non-tracking surface scan systems, where the vertical pattern may remain constant. Owing to its lower cost and less wind exposure, shipboard, airport surface, and harbour

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Jamming is problematic to radar since the jamming signal only needs to travel one way (from the jammer to the radar receiver) whereas the radar echoes travel two ways (radar-target-radar) and are therefore significantly reduced in power by the time they return to the radar receiver in accordance with

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certain height. Monopulse can be improved by altering the elevation algorithm used at low elevation. In newer air traffic control radar equipment, algorithms are used to identify the false targets by comparing the current pulse returns to those adjacent, as well as calculating return improbabilities.

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to monitor vehicle speeds on the roads. Automotive radars are used for adaptive cruise control and emergency breaking on vehicles by ignoring stationary roadside objects that could cause incorrect brake application and instead measuring moving objects to prevent collision with other vehicles. As part

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Given all required funding and development support, the team produced working radar systems in 1935 and began deployment. By 1936, the first five Chain Home (CH) systems were operational and by 1940 stretched across the entire UK including Northern Ireland. Even by standards of the era, CH was crude;

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Phased array antennas are composed of evenly spaced similar antenna elements, such as aerials or rows of slotted waveguide. Each antenna element or group of antenna elements incorporates a discrete phase shift that produces a phase gradient across the array. For example, array elements producing a 5

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to produce the display showing different frequencies. Each different distance produces a different spectrum. These spectra are used to perform the detection process. This is required to achieve acceptable performance in hostile environments involving weather, terrain, and electronic countermeasures.

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The two techniques outlined above both have their disadvantages. The pulse timing technique has an inherent tradeoff in that the accuracy of the distance measurement is inversely related to the length of the pulse, while the energy, and thus direction range, is directly related. Increasing power for

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riding on the receive signal is proportional to the time delay between the radar and the reflector. The frequency shift becomes greater with greater time delay. The frequency shift is directly proportional to the distance travelled. That distance can be displayed on an instrument, and it may also be

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These two effects tend to be at odds with each other, and it is not easy to combine both good short range and good long range in a single radar. This is because the short pulses needed for a good minimum range broadcast have less total energy, making the returns much smaller and the target harder to

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Noise is also generated by external sources, most importantly the natural thermal radiation of the background surrounding the target of interest. In modern radar systems, the internal noise is typically about equal to or lower than the external noise. An exception is if the radar is aimed upwards at

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Terrestrial radar uses low-power FM signals that cover a larger frequency range. The multiple reflections are analyzed mathematically for pattern changes with multiple passes creating a computerized synthetic image. Doppler effects are used which allows slow moving objects to be detected as well as

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Another form of distance measuring radar is based on frequency modulation. In these systems, the frequency of the transmitted signal is changed over time. Since the signal takes a finite time to travel to and from the target, the received signal is a different frequency than what the transmitter is

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or a physical impossibility. Terrain bounce jamming exploits this response by amplifying the radar signal and directing it downward. These problems can be overcome by incorporating a ground map of the radar's surroundings and eliminating all echoes which appear to originate below ground or above a

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Clutter is detected and neutralized in several ways. Clutter tends to appear static between radar scans; on subsequent scan echoes, desirable targets will appear to move, and all stationary echoes can be eliminated. Sea clutter can be reduced by using horizontal polarization, while rain is reduced

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processing is required to identify the true range of all reflected signals. Radial movement is usually linked with Doppler frequency to produce a lock signal that cannot be produced by radar jamming signals. Pulse-Doppler signal processing also produces audible signals that can be used for threat

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to avoid detection until an attack vehicle is too close to destroy. Pulse-Doppler signal processing incorporates more sophisticated electronic filtering that safely eliminates this kind of weakness. This requires the use of medium pulse-repetition frequency with phase coherent hardware that has a

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was the first to use radio waves to detect "the presence of distant metallic objects". In 1904, he demonstrated the feasibility of detecting a ship in dense fog, but not its distance from the transmitter. He obtained a patent for his detection device in April 1904 and later a patent for a related

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As the price of electronics has fallen, phased array radars have become more common. Almost all modern military radar systems are based on phased arrays, where the small additional cost is offset by the improved reliability of a system with no moving parts. Traditional moving-antenna designs are

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The information provided by radar includes the bearing and range (and therefore position) of the object from the radar scanner. It is thus used in many different fields where the need for such positioning is crucial. The first use of radar was for military purposes: to locate air, ground and sea

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weather radar uses a symmetric antenna to perform detailed volumetric scans of the atmosphere. Spoiled parabolic antennas produce a narrow beam in one dimension and a relatively wide beam in the other. This feature is useful if target detection over a wide range of angles is more important than

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consists of three flat surfaces meeting like the inside corner of a cube. The structure will reflect waves entering its opening directly back to the source. They are commonly used as radar reflectors to make otherwise difficult-to-detect objects easier to detect. Corner reflectors on boats, for

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Opposing the move to smaller wavelengths are a number of practical issues. For one, the electronics needed to produce high power very short wavelengths were generally more complex and expensive than the electronics needed for longer wavelengths or didn't exist at all. Another issue is that the

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to measure radial wind velocity and precipitation rate in each different volume of air. This is linked with computing systems to produce a real-time electronic weather map. Aircraft safety depends upon continuous access to accurate weather radar information that is used to prevent injuries and

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often operating in the tens of megawatts. The continuous wave methods spread this energy out in time and thus require much lower peak power compared to pulse techniques, but requires some method of allowing the sent and received signals to operate at the same time, often demanding two separate

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screens by operators who thereby give radio landing instructions to the pilot, maintaining the aircraft on a defined approach path to the runway. Military fighter aircraft are usually fitted with air-to-air targeting radars, to detect and target enemy aircraft. In addition, larger specialized

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discovered that ships passing through the beam path caused the received signal to fade in and out. Taylor submitted a report, suggesting that this phenomenon might be used to detect the presence of ships in low visibility, but the Navy did not immediately continue the work. Eight years later,

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The introduction of new electronics in the 1960s allowed the two techniques to be combined. It starts with a longer pulse that is also frequency modulated. Spreading the broadcast energy out in time means lower peak energies can be used, with modern examples typically on the order of tens of

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and turned the request over to Wilkins. Wilkins returned a set of calculations demonstrating the system was basically impossible. When Watson-Watt then asked what such a system might do, Wilkins recalled the earlier report about aircraft causing radio interference. This revelation led to the

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degree phase shift for each wavelength across the array face will produce a beam pointed 5 degrees away from the centerline perpendicular to the array face. Signals travelling along that beam will be reinforced. Signals offset from that beam will be cancelled. The amount of reinforcement is

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As an example, a Doppler weather radar with a pulse rate of 2 kHz and transmit frequency of 1 GHz can reliably measure weather speed up to at most 150 m/s (340 mph), thus cannot reliably determine radial velocity of aircraft moving 1,000 m/s (2,200 mph).

524:, produced an experimental apparatus, RAPID, capable of detecting an aircraft within 3 km of a receiver. The Soviets produced their first mass production radars RUS-1 and RUS-2 Redut in 1939 but further development was slowed following the arrest of Oshchepkov and his subsequent 3668:, such multiple aperture arrays, when used in transmitters, result in narrow beams at the expense of reducing the total power transmitted to the target. In principle, such techniques could increase spatial resolution, but the lower power means that this is generally not effective. 3145:(CW radar), by sending out a very pure signal of a known frequency. CW radar is ideal for determining the radial component of a target's velocity. CW radar is typically used by traffic enforcement to measure vehicle speed quickly and accurately where the range is not important. 3696:. This provides a strong incentive to use shorter wavelengths as this will result in smaller antennas. Shorter wavelengths also result in higher resolution due to diffraction, meaning the shaped reflector seen on most radars can also be made smaller for any desired beamwidth. 2584:

amplification. Another reason for heterodyne processing is that for fixed fractional bandwidth, the instantaneous bandwidth increases linearly in frequency. This allows improved range resolution. The one notable exception to heterodyne (downconversion) radar systems is

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Very long range, ground penetrating; 'very high frequency'. Early radar systems generally operated in VHF as suitable electronics had already been developed for broadcast radio. Today this band is heavily congested and no longer suitable for radar due to interference.

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tactic, or unintentional, as with friendly forces operating equipment that transmits using the same frequency range. Jamming is considered an active interference source, since it is initiated by elements outside the radar and in general unrelated to the radar signals.

425:(NRL) observed similar fading effects from passing aircraft; this revelation led to a patent application as well as a proposal for further intensive research on radio-echo signals from moving targets to take place at NRL, where Taylor and Young were based at the time. 2690:

Radar systems must overcome unwanted signals in order to focus on the targets of interest. These unwanted signals may originate from internal and external sources, both passive and active. The ability of the radar system to overcome these unwanted signals defines its

3000:, reflect off a target, and return to the radar antenna. Since a nautical mile is defined as 1,852 m, then dividing this distance by the speed of light (299,792,458 m/s), and then multiplying the result by 2 yields a result of 12.36 μs in duration. 3925:

radar; short-range tracking. Named X band because the frequency was a secret during WW2. Diffraction off raindrops during heavy rain limits the range in the detection role and makes this suitable only for short-range roles or those that deliberately detect rain.

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Historical information is accumulated and used to predict future position for use with air traffic control, threat estimation, combat system doctrine, gun aiming, and missile guidance. Position data is accumulated by radar sensors over the span of a few minutes.

789:, aircraft can be equipped with radar devices that warn of aircraft or other obstacles in or approaching their path, display weather information, and give accurate altitude readings. The first commercial device fitted to aircraft was a 1938 Bell Lab unit on some 3606:. The massive redundancy associated with having a large number of array elements increases reliability at the expense of gradual performance degradation that occurs as individual phase elements fail. To a lesser extent, Phased array radars have been used in 1060:

Radar waves scatter in a variety of ways depending on the size (wavelength) of the radio wave and the shape of the target. If the wavelength is much shorter than the target's size, the wave will bounce off in a way similar to the way light is reflected by a

361:. It operated on a 50 cm wavelength and the pulsed radar signal was created via a spark-gap. His system already used the classic antenna setup of horn antenna with parabolic reflector and was presented to German military officials in practical tests in 1085:

example, make them more detectable to avoid collision or during a rescue. For similar reasons, objects intended to avoid detection will not have inside corners or surfaces and edges perpendicular to likely detection directions, which leads to "odd" looking

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are used to measure the bearing and distance of ships to prevent collision with other ships, to navigate, and to fix their position at sea when within range of shore or other fixed references such as islands, buoys, and lightships. In port or in harbour,

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is the change in distance to an object with respect to time. Thus the existing system for measuring distance, combined with a memory capacity to see where the target last was, is enough to measure speed. At one time the memory consisted of a user making

2473: 1065:. If the wavelength is much longer than the size of the target, the target may not be visible because of poor reflection. Low-frequency radar technology is dependent on resonances for detection, but not identification, of targets. This is described by 3453:

for reception, each on a different display. The maximum return would be detected with an antenna at right angles to the target, and a minimum with the antenna pointed directly at it (end on). The operator could determine the direction to a target by

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Radio signals broadcast from a single antenna will spread out in all directions, and likewise a single antenna will receive signals equally from all directions. This leaves the radar with the problem of deciding where the target object is located.

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had an article in which a U.S. scientist speculated about the British early warning system on the English east coast and came close to what it was and how it worked. Watson-Watt was sent to the U.S. in 1941 to advise on air defense after Japan's

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dive bombers. More than 230 Gneiss-2 stations were produced by the end of 1944. The French and Soviet systems, however, featured continuous-wave operation that did not provide the full performance ultimately synonymous with modern radar systems.

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Moderate range surveillance, Terminal air traffic control, long-range weather, marine radar; 'S' for 'sentimetric', its code-name during WWII. Less efficient than L, but offering higher resolution, making them especially suitable for long-range

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rely on the Doppler effect to enhance performance. This produces information about target velocity during the detection process. This also allows small objects to be detected in an environment containing much larger nearby slow moving objects.

861:, fixed-position stopped vehicle detection (SVD) radars are mounted on the roadside to detect stranded vehicles, obstructions and debris by inverting the automotive radar approach and ignoring moving objects. Smaller radar systems are used to 3148:

When using a pulsed radar, the variation between the phase of successive returns gives the distance the target has moved between pulses, and thus its speed can be calculated. Other mathematical developments in radar signal processing include

1073:. Early radars used very long wavelengths that were larger than the targets and thus received a vague signal, whereas many modern systems use shorter wavelengths (a few centimetres or less) that can image objects as small as a loaf of bread. 564: 3458:

the antenna so one display showed a maximum while the other showed a minimum. One serious limitation with this type of solution is that the broadcast is sent out in all directions, so the amount of energy in the direction being examined is

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A Track algorithm is a radar performance enhancement strategy. Tracking algorithms provide the ability to predict future position of multiple moving objects based on the history of the individual positions being reported by sensor systems.

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But by 1940, it was the British who had made a spectacular breakthrough: the resonant cavity magnetron, a radar transmitter far more powerful than its predecessors.... The magnetron stunned the Americans. Their research was years off the

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Pulse-Doppler signal processing includes frequency filtering in the detection process. The space between each transmit pulse is divided into range cells or range gates. Each cell is filtered independently much like the process used by a

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Only the radial component of the velocity is relevant. When the reflector is moving at right angle to the radar beam, it has no relative velocity. Objects moving parallel to the radar beam produce the maximum Doppler frequency shift.

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and cannot fully be eliminated when directly facing a jammer which uses the same frequency and polarization as the radar. Sidelobe jamming can be overcome by reducing receiving sidelobes in the radar antenna design and by using an

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of the wave. For a transmitted radar signal, the polarization can be controlled to yield different effects. Radars use horizontal, vertical, linear, and circular polarization to detect different types of reflections. For example,

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It not only changed the course of the war by allowing us to develop airborne radar systems, it remains the key piece of technology that lies at the heart of your microwave oven today. The cavity magnetron's invention changed the

492:, and the United States, independently and in great secrecy, developed technologies that led to the modern version of radar. Australia, Canada, New Zealand, and South Africa followed prewar Great Britain's radar development, and 3329:

Radar video returns from aircraft can be subjected to a plot extraction process whereby spurious and interfering signals are discarded. A sequence of target returns can be monitored through a device known as a plot extractor.

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Frequency shift is caused by motion that changes the number of wavelengths between the reflector and the radar. This can degrade or enhance radar performance depending upon how it affects the detection process. As an example,

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Doppler shift depends upon whether the radar configuration is active or passive. Active radar transmits a signal that is reflected back to the receiver. Passive radar depends upon the object sending a signal to the receiver.

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Mapping, short range, airport surveillance; frequency just above K band (hence 'a') Photo radar, used to trigger cameras which take pictures of license plates of cars running red lights, operates at 34.300 ± 0.100 GHz.

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Clutter refers to radio frequency (RF) echoes returned from targets which are uninteresting to radar operators. Such targets include man-made objects such as buildings and — intentionally — by radar countermeasures such as

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or sawtooth pattern at audio frequencies. The signal is then sent out from one antenna and received on another, typically located on the bottom of the aircraft, and the signal can be continuously compared using a simple

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used radio technology to provide advance warning of thunderstorms to airmen and during the 1920s went on to lead the U.K. research establishment to make many advances using radio techniques, including the probing of the

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The non-relevant real time returns can be removed from the displayed information and a single plot displayed. In some radar systems, or alternatively in the command and control system to which the radar is connected, a

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Noise typically appears as random variations superimposed on the desired echo signal received in the radar receiver. The lower the power of the desired signal, the more difficult it is to discern it from the noise. The

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axis represents each successive transmit pulse interval during which samples are taken. The Fast Fourier Transform process converts time-domain samples into frequency domain spectra. This is sometimes called the

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Radar jamming refers to radio frequency signals originating from sources outside the radar, transmitting in the radar's frequency and thereby masking targets of interest. Jamming may be intentional, as with an

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Parabolic reflectors can be either symmetric parabolas or spoiled parabolas: Symmetric parabolic antennas produce a narrow "pencil" beam in both the X and Y dimensions and consequently have a higher gain. The

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and formation of highly flammable alcohol. The loss of a U.S. Navy aircraft in 1978 was attributed to a silicate ester fire. Coolanol is also expensive and toxic. The U.S. Navy has instituted a program named

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to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds.

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on either side used instead for surveillance. K-band is used for detecting clouds by meteorologists, and by police for detecting speeding motorists. K-band radar guns operate at 24.150 ± 0.100 GHz.

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The weak absorption of radio waves by the medium through which they pass is what enables radar sets to detect objects at relatively long ranges—ranges at which other electromagnetic wavelengths, such as

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Radar sensitivity and the power of the return signal as computed in the radar equation. This component includes factors such as the environmental conditions and the size (or radar cross section) of the

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Radar receivers are usually, but not always, in the same location as the transmitter. The reflected radar signals captured by the receiving antenna are usually very weak. They can be strengthened by

3489:"dish" to create a tight broadcast beam, typically using the same dish as the receiver. Such systems often combine two radar frequencies in the same antenna in order to allow automatic steering, or 4592: 2835:

that subtracts the received signal from two successive pulses using phase to reduce signals from slow-moving objects. This can be adapted for systems that lack a coherent transmitter, such as

1337: 3613:. As of 2017, NOAA plans to implement a national network of Multi-Function Phased array radars throughout the United States within 10 years, for meteorological studies and flight monitoring. 660:; without it, significant numbers of fighter aircraft, which Great Britain did not have available, would always have needed to be in the air to respond quickly. The radar formed part of the " 4029:

or use in space where attenuation is not a problem. Multiple letters are assigned to these bands by different groups. These are from Baytron, a now defunct company that made test equipment.

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Noise is random and target signals are not. Signal processing can take advantage of this phenomenon to reduce the noise floor using two strategies. The kind of signal integration used with

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The traditional band names originated as code-names during World War II and are still in military and aviation use throughout the world. They have been adopted in the United States by the

2123: 656:" along the East and South coasts of England in time for the outbreak of World War II in 1939. This system provided the vital advance information that helped the Royal Air Force win the 1076:

Short radio waves reflect from curves and corners in a way similar to glint from a rounded piece of glass. The most reflective targets for short wavelengths have 90° angles between the

507:(CSF) headed by Maurice Ponte with Henri Gutton, Sylvain Berline and M. Hugon, began developing an obstacle-locating radio apparatus, aspects of which were installed on the ocean liner 2831:, so individual signals can be separated from multiple reflectors located in the same volume using velocity differences. This requires a coherent transmitter. Another technique uses a 5320: 3118:

If the transmitter's output is coherent (phase synchronized), there is another effect that can be used to make almost instant speed measurements (no memory is required), known as the

618:, was very impressed with their system's potential and funds were immediately provided for further operational development. Watson-Watt's team patented the device in patent GB593017. 436:

test unit, operating at 50 cm (600 MHz) and using pulsed modulation which gave successful laboratory results. In January 1931, a writeup on the apparatus was entered in the

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rather than radio waves. With the emergence of driverless vehicles, radar is expected to assist the automated platform to monitor its environment, thus preventing unwanted incidents.

1037:, or a significant change in atomic density between the object and what is surrounding it, will usually scatter radar (radio) waves from its surface. This is particularly true for 2307: 5424: 4714:

is actually an acronym that stands for RAdio Detection and Ranging. It was officially coined by U.S. Navy Lieutenant Commanders Samuel M. Tucker and F.R. Furth in November 1940

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Secondary Scan: A scanning technique where the antenna feed is moved to produce a scanning beam, examples include conical scan, unidirectional sector scan, lobe switching, etc.

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Palmer Scan: A scanning technique that produces a scanning beam by moving the main antenna and its feed. A Palmer Scan is a combination of a Primary Scan and a Secondary Scan.

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McGraw-Hill dictionary of scientific and technical terms / Daniel N. Lapedes, editor in chief. Lapedes, Daniel N. New York; Montreal : McGraw-Hill, 1976. , 1634, A26 p.

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caused by the passage of a third vessel. In his report, Popov wrote that this phenomenon might be used for detecting objects, but he did nothing more with this observation.

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techniques, using an array of separate dishes that are phased into a single effective aperture, are not typical for radar applications, although they are widely used in

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possible in certain cases. The radar signals that are reflected back towards the radar receiver are the desirable ones that make radar detection work. If the object is

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is produced by electrons in transit across a discontinuity, which occurs in all detectors. Shot noise is the dominant source in most receivers. There will also be

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in many directions, although some of them will be absorbed and penetrate into the target. Radar signals are reflected especially well by materials of considerable

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maintained by the Royal Engineers. This is the first official record in Great Britain of the technology that was used in coastal defence and was incorporated into

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Verfahren zur Bestimmung der Entfernung von metallischen Gegenständen (Schiffen o. dgl.), deren Gegenwart durch das Verfahren nach Patent 16556 festgestellt wird.

3827:), ground penetrating, foliage penetrating; 'ultra high frequency'. Efficiently produced and received at very high energy levels, and also reduces the effects of 1122: 1097:, are very reflective but do not direct the scattered energy back toward the source. The extent to which an object reflects or scatters radio waves is called its 1573:

This shows that the received power declines as the fourth power of the range, which means that the received power from distant targets is relatively very small.

504: 3807:'P' for 'previous', applied retrospectively to early radar systems; essentially HF + VHF. Often used for remote sensing because of good vegetation penetration. 1756: 4079:

High voltage switch for non-coherent keyed power-oscillators These modulators consist of a high voltage pulse generator formed from a high voltage supply, a

4726: 4159:(P2) to eliminate or reduce the volume and toxicity of waste, air emissions, and effluent discharges. Because of this, Coolanol is used less often today. 7123: 698:

in the UK, which allowed the creation of relatively small systems with sub-meter resolution. Britain shared the technology with the U.S. during the 1940

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emitted by the target objects themselves, such as infrared radiation (heat). This process of directing artificial radio waves towards objects is called

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waveform. This waveform can be generated by low power/low-voltage input signals. In this case the radar transmitter must be a power-amplifier, e.g., a

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Primary Scan: A scanning technique where the main antenna aerial is moved to produce a scanning beam, examples include circular scan, sector scan, etc.

1458: 521: 610:

shortwave transmitter as the source and their GPO receiver setup in a field while a bomber flew around the site. When the plane was clearly detected,

3712: 5165: 357:

amendment for estimating the distance to the ship. He also obtained a British patent on 23 September 1904 for a full radar system, that he called a

5648: 4827: 741:

The war precipitated research to find better resolution, more portability, and more features for radar, including small, lightweight sets to equip

6679: 3623:

Phased array radars are valued for use in aircraft since they can track multiple targets. The first aircraft to use a phased array radar was the

734:, Cambridge, Massachusetts which developed microwave radar technology in the years 1941–45. Later, in 1943, Page greatly improved radar with the 4694: 3205:

The primary purpose is to measure both the amplitude and frequency of the aggregate reflected signal from multiple distances. This is used with

6812: 1764: 5934: 4845: 3921:, weather, medium-resolution mapping and ground surveillance; in the United States the narrow range 10.525 GHz ±25 MHz is used for 401:

model after noting its manual's description of a "fading" effect (the common term for interference at the time) when aircraft flew overhead.

5980: 5822:. Melbourne, Australia: Aeronautical Research Laboratory, Defense Science and Technology Organisation, Department of Defense. Archived from 5328: 3594:), but electronic device limitations led to poor performance. Phased array radars were originally used for missile defence (see for example 2969:

Pulse radar: The round-trip time for the radar pulse to get to the target and return is measured. The distance is proportional to this time.

2554:

that affect range performance. Reflectors that are too far away produce too little signal to exceed the noise floor and cannot be detected.

2161: 5938:". Privateline.com. (Anecdotal account of the carriage of the world's first high power cavity magnetron from Britain to the US during WW2.) 3394:

that serves as a switch between the antenna and the transmitter or the receiver for the signal when the antenna is used in both situations.

644:

Development of radar greatly expanded on 1 September 1936, when Watson-Watt became superintendent of a new establishment under the British

6109:

The invention that changed the world: how a small group of radar pioneers won the Second World War and launched a technological revolution

2637:) this noise source cannot be further eroded. Ultimately, radar, like all macro-scale entities, is profoundly impacted by quantum theory. 2551: 2805: 802:

military aircraft carry powerful airborne radars to observe air traffic over a wide region and direct fighter aircraft towards targets.

5683: 5413: 5139: 2065:, since the returned frequency otherwise cannot be distinguished from shifting of a harmonic frequency above or below, thus requiring: 1853: 4194:

based on the comparison of reference signals with radio signals reflected, or retransmitted, from the position to be determined. Each

5701: 4909:

Hyland, L.A, A.H. Taylor, and L.C. Young; "System for detecting objects by radio," U.S. Patent No. 1981884, granted 27 November 1934

5876: 2828: 652:, near Felixstowe, Suffolk. Work there resulted in the design and installation of aircraft detection and tracking stations called " 7143: 7133: 6390: 5549: 3616:

Phased array antennas can be built to conform to specific shapes, like missiles, infantry support vehicles, ships, and aircraft.

540:

Full radar evolved as a pulsed system, and the first such elementary apparatus was demonstrated in December 1934 by the American

6901: 6802: 6003: 5117: 4381: 3824: 3463:

of that transmitted. To get a reasonable amount of power on the "target", the transmitting aerial should also be directional.

3034:. In these systems a "carrier" radar signal is frequency modulated in a predictable way, typically varying up and down with a 1587:= 1 is a simplification for transmission in a vacuum without interference. The propagation factor accounts for the effects of 6497: 6451: 6372: 6357: 6342: 6324: 6305: 6286: 6267: 6248: 6229: 6207: 6188: 6169: 6150: 6134: 6116: 6097: 6078: 6059: 6040: 5509: 4947: 4179: 3719:. Most countries have additional regulations to control which parts of each band are available for civilian or military use. 3716: 3317: 2836: 2509:

Line of sight, which depends on the height above the ground. Without a direct line of sight, the path of the beam is blocked.

1029:

from the first, the waves will reflect or scatter from the boundary between the materials. This means that a solid object in

731: 5399: 4742:"Performance Assessment of an Integrated Radar Architecture for Multi-Types Frontal Object Detection for Autonomous Vehicle" 6622: 5279: 4276: 3635: 3055:. This signal processing is similar to that used in speed detecting Doppler radar. Example systems using this approach are 2726:. Such targets also include natural objects such as ground, sea, and — when not being tasked for meteorological purposes — 2516:. The maximum non-ambiguous range is the distance the pulse can travel to and return from before the next pulse is emitted. 4940:

The Origins and Development of Radar in the Royal Navy, 1935–45 with Particular Reference to Decimetric Gunnery Equipments

4663: 3338:

is used to associate the sequence of plots belonging to individual targets and estimate the targets' headings and speeds.

6807: 6672: 6641:

A set of 10 video lectures developed at Lincoln Laboratory to develop an understanding of radar systems and technologies.

6015: 5823: 4106:

or a solid state transmitter. In this way, the transmitted pulse is intrapulse-modulated and the radar receiver must use

3642: 2930: 5280:"Scotland's little-known WWII hero who helped beat the Luftwaffe with invention of radar set to be immortalised in film" 2539:

Signal noise is an internal source of random variations in the signal, which is generated by all electronic components.

6536: 6476: 5441: 4556: 4227:

Radar come in a variety of configurations in the emitter, the receiver, the antenna, wavelength, scan strategies, etc.

4061:

Used as a visual sensor for experimental autonomous vehicles, high-resolution meteorological observation, and imaging.

2502:

sinks below the horizon. Furthermore, the signal is attenuated by the medium the beam crosses, and the beam disperses.

1293: 615: 6487: 2490:

A radar beam follows a linear path in vacuum but follows a somewhat curved path in atmosphere due to variation in the

7020: 6638: 6422: 6403: 5904: 5727: 5616: 3620:

still widely used in roles where cost is a significant factor such as air traffic surveillance and similar systems.

3415:

An electronic section that controls all those devices and the antenna to perform the radar scan ordered by software.

2901:. Jammers therefore can be much less powerful than their jammed radars and still effectively mask targets along the 5378: 2071: 1630:

can interact with Doppler to produce signal cancellation at certain radial velocities, which degrades performance.

1069:, an effect that creates Earth's blue sky and red sunsets. When the two length scales are comparable, there may be 3231: 3043:

modulator that produces an audio frequency tone from the returned signal and a portion of the transmitted signal.

1057:. This is the radio equivalent of painting something a dark colour so that it cannot be seen by the eye at night. 7113: 4215: 3259: 3170: 2685: 2669: 2034:. As a result, the Doppler measurement is only non-ambiguous if the Doppler frequency shift is less than half of 1013:). The radar's frequency, pulse form, polarization, signal processing, and antenna determine what it can observe. 5771: 5091: 2570:

is a measure of the noise produced by a receiver compared to an ideal receiver, and this needs to be minimized.

711:

showed an example of a radar unit using the Watson-Watt patent in an article on air defence. Also, in late 1941

66:

Radar of the type used for detection of aircraft. It rotates steadily, sweeping the airspace with a narrow beam.

7108: 6665: 4393: 4156: 4091:, a special type of vacuum tube that converts DC (usually pulsed) into microwaves. This technology is known as 3879: 3692:

Antennas generally have to be sized similar to the wavelength of the operational frequency, normally within an

3267: 3211: 2259:, the electric field is perpendicular to the direction of propagation, and the electric field direction is the 456: 4920: 4798:

Patent DE165546; Verfahren, um metallische Gegenstände mittels elektrischer Wellen einem Beobachter zu melden.

7103: 7098: 2468:{\displaystyle H=\left({\sqrt {r^{2}+(k_{e}a_{e})^{2}+2rk_{e}a_{e}sin(\theta _{e})}}\right)-k_{e}a_{e}+h_{a}} 858: 3047: 2909:). Jammers have an added effect of affecting radars along other lines of sight through the radar receiver's 528:

sentence. In total, only 607 Redut stations were produced during the war. The first Russian airborne radar,

7128: 7118: 7007: 7002: 6987: 6906: 6740: 5351: 5029: 4366: 3674:

by post-processing motion data from a single moving source, on the other hand, is widely used in space and

3263: 2542:

Reflected signals decline rapidly as distance increases, so noise introduces a radar range limitation. The

1041:

materials such as metal and carbon fibre, making radar well-suited to the detection of aircraft and ships.

895: 5945: 4095:. In this way, the transmitted pulse of RF radiation is kept to a defined and usually very short duration. 3526:: The radar beam is rotated in a small circle around the "boresight" axis, which is pointed at the target. 3401:. Knowing the shape of the desired received signal (a pulse), an optimal receiver can be designed using a 6896: 5753: 5006:

Frederick Seitz, Norman G. Einspruch, Electronic Genie: The Tangled History of Silicon – 1998 – page 104

3646: 3312: 2882: 1093:, especially at longer wavelengths. Half wavelength long wires or strips of conducting material, such as 869:

for computer interaction. Automatic door opening, light activation and intruder sensing are also common.

817: 754: 746: 500: 322: 882: 6982: 6941: 5015:

John Erickson. Radio-Location and the Air Defence Problem: The Design and Development of Soviet Radar.

4191: 3727: 3235: 2513: 1840: 794: 7138: 6720: 5886: 5161: 4452: 4398: 3898:

Satellite transponders; a compromise (hence 'C') between X and S bands; weather; long range tracking

3347: 3275: 3052: 2902: 2842: 2746:

trails. Radar clutter can also be caused by other atmospheric phenomena, such as disturbances in the

2256: 1577: 1018: 773: 545: 461: 422: 268: 256: 6519: 5790: 4823: 3115:. Modern radar systems perform the equivalent operation faster and more accurately using computers. 782:

targets. This evolved in the civilian field into applications for aircraft, ships, and automobiles.

4849: 4403: 4271: 3671: 3255: 2832: 2641: 1634: 1627: 1042: 845: 798: 750: 727: 283: 264: 6576:

Robert Calderbank; S. Howard; Bill Moran (2009). "Waveform diversity in radar signal processing".

4871: 3535: 3433: 5665: 4432: 4341: 3446: 3150: 2926: 2852:

Clutter may also originate from multipath echoes from valid targets caused by ground reflection,

2786: 2739: 2647: 921: 394: 386: 385:

at long distances. Through his lightning experiments, Watson-Watt became an expert on the use of

131: 428:

Similarly, in the UK, L. S. Alder took out a secret provisional patent for Naval radar in 1928.

6880: 6776: 5498: 4283: 3773: 3705: 3471: 2846: 2775: 2723: 2498:. Even when the beam is emitted parallel to the ground, the beam rises above the ground as the 2294: 1094: 810: 719: 221: 194: 162: 31: 17: 4989: 4075:

act to provide the waveform of the RF-pulse. There are two different radar modulator designs:

1348: 682: 353: 6972: 6962: 6946: 5240: 5072: 4236: 4211: 4183: 4080: 3675: 3279: 3142: 3027: 2865: 2794: 2692: 2547: 2265: 1588: 1046: 1038: 1030: 1010: 677: 473: 338: 326: 252: 185:, which allowed the creation of relatively small systems with sub-meter resolution. The term 51: 5687: 5147: 1244:{\displaystyle P_{r}={\frac {P_{t}G_{t}A_{r}\sigma F^{4}}{{(4\pi )}^{2}R_{t}^{2}R_{r}^{2}}}} 212:

The modern uses of radar are highly diverse, including air and terrestrial traffic control,

157:, a receiving antenna (often the same antenna is used for transmitting and receiving) and a 6585: 5956: 5847:

ITU Radio Regulations, Section IV. Radio Stations and Systems – Article 1.100, definition:

5571: 5261: 4635: 3218: 3017: 2974: 2938: 2590: 2260: 2250: 2131: 2037: 2010: 1983: 1956: 1929: 1714: 1687: 1660: 1077: 996: 980: 913: 248: 217: 142: 87: 3945:

High-resolution, also used for satellite transponders, frequency under K band (hence 'u')

2589:

radar. Here a single cycle, or transient wave, is used similar to UWB communications, see

979:

Radar relies on its own transmissions rather than light from the Sun or the Moon, or from

777:

Commercial marine radar antenna. The rotating antenna radiates a vertical fan-shaped beam.

8: 6837: 6797: 6715: 6705: 5705: 5540: 4885: 4746:

2018 IEEE International Conference on Automatic Control and Intelligent Systems (I2CACIS)

4467: 4447: 4371: 4329: 4126: 4099: 3858: 3665: 3599: 3271: 3127: 3087: 2824: 2801:

to detect precipitation). Other methods attempt to increase the signal-to-clutter ratio.

2798: 2673: 2672:, which reduces the noise floor by the number of filters. These improvements depend upon 2530: 2499: 2269: 1638: 1608: 1385: 1098: 1066: 1022: 866: 603: 517: 398: 276: 6649: 6589: 4639: 3730:

industries, have replaced the traditional military designations with their own systems.

3590:

Phased array radars have been in use since the earliest years of radar in World War II (

2272:

returns usually indicate metal surfaces. Random polarization returns usually indicate a

1591:

and shadowing and depends on the details of the environment. In a real-world situation,

7049: 6710: 6601: 6507: 6468:

Signal design for good correlation: for wireless communication, cryptography, and radar

6433: 6216:

Kaiser, Gerald, Chapter 10 in "A Friendly Guide to Wavelets", Birkhauser, Boston, 1994.

5525:

M. Castelaz. "Exploration: The Doppler Effect". Pisgah Astronomical Research Institute.

5356: 4525: 4356: 4307: 4261: 3693: 3657: 3460: 3226: 3158: 2898: 2889: 2630: 1741: 1287: 1054: 590: 579: 549: 541: 493: 418: 373: 233: 190: 103: 5647:. Syracuse Research Corporation; Massachusetts Institute of Technology. Archived from 3086:

longer range while maintaining accuracy demands extremely high peak power, with 1960s

560: 7093: 7044: 6618: 6532: 6493: 6472: 6447: 6418: 6399: 6368: 6353: 6338: 6320: 6301: 6282: 6263: 6244: 6225: 6203: 6184: 6165: 6146: 6130: 6112: 6093: 6074: 6055: 6036: 5996: 5505: 4943: 4741: 4720: 4479: 4287: 4107: 3595: 3544: 3480: 3247: 3198: 3161:

which makes use of the change of frequency of returns from moving targets ("chirp").

3080: 2934: 2751: 2062: 1980:, the resulting frequency spectrum will contain harmonic frequencies above and below 968: 952: 758: 723: 713: 657: 553: 429: 346: 6605: 5125: 4809: 4796: 4520: 3687: 3012:

Continuous wave (CW) radar. Using frequency modulation allows range to be extracted.

1576:

Additional filtering and pulse integration modifies the radar equation slightly for

1416:

In the common case where the transmitter and the receiver are at the same location,

865:. Examples are breathing pattern detection for sleep monitoring and hand and finger 397:

to conduct an extensive review of available shortwave units. Wilkins would select a

393:

transmission. Requiring a suitable receiver for such studies, he told the "new boy"

202: 6593: 6564: 4765:

Kostenko, A.A., A.I. Nosich, and I.A. Tishchenko, "Radar Prehistory, Soviet Side,"

4643: 4437: 4427: 4351: 4321: 4088: 3828: 3558: 3523: 3398: 3222: 2853: 2771: 2759: 2703: 2491: 1086: 1081: 912:

in predetermined directions. When these signals contact an object they are usually

821: 790: 762: 695: 481: 469: 341:. In 1897, while testing this equipment for communicating between two ships in the 307: 272: 260: 237: 178: 6936: 6644: 5184: 3175: 987:, although radio waves are invisible to the human eye as well as optical cameras. 559:

at night. This design was followed by a pulsed system demonstrated in May 1935 by

6931: 6926: 6761: 6756: 6007: 5949: 5607: 5584: 4251: 4207: 4125:

Coherent microwave amplifiers operating above 1,000 watts microwave output, like

4018: 3962: 3661: 3603: 3428: 3295: 3031: 2817:

Doppler processing, which uses filters to separate clutter from desirable signals

2716: 2580:

caused by electron transit through amplification devices, which is reduced using

1844: 1646: 1563:{\displaystyle P_{r}={{P_{t}G_{t}A_{r}\sigma F^{4}} \over {{(4\pi )}^{2}R^{4}}}.} 936:

either toward or away from the transmitter, there will be a slight change in the

929: 862: 849: 735: 707: 569: 485: 229: 213: 154: 119: 99: 95: 6546:

E. Fishler; A. Haimovich; R. Blum; D. Chizhik; L. Cimini; R. Valenzuela (2004).

4202:

in which it operates permanently or temporarily. Typical radar utilizations are

3550:

surveillance radars now use this approach in preference to a parabolic antenna.

206: 7088: 6832: 6335:

Not an Ordinary Life. How Changing Times Brought Historical Events into my Life

5575: 5211: 4671: 4515: 4506: 4415: 4376: 4335: 4231: 3755: 3701: 3653: 3628: 3402: 3119: 2982: 2978: 2960: 2804:

Clutter moves with the wind or is stationary. Two common strategies to improve

2586: 2505:

The maximum range of conventional radar can be limited by a number of factors:

964: 941: 825: 699: 661: 638: 597:

In 1935, Watson-Watt was asked to judge recent reports of a German radio-based

533: 445: 409: 318: 291: 182: 158: 146: 6612: 5796:. Madrid, Spain: Instituto de Física Aplicada, CETEF "L. Torres Quevedo", CSIC 5669: 4045:

Very strongly absorbed by atmospheric oxygen, which resonates at 60 GHz.

3708:. For this reason, a wide variety of wavelengths are used in different roles. 3638:

radar was considered to be the world's most powerful fighter radar, until the

1613: 813:

radar systems are used to monitor and regulate ship movements in busy waters.

7082: 6771: 6700: 6657: 4535: 4346: 4266: 4256: 4241: 4203: 3950: 3887: 3501: 3409: 3335: 3291: 3206: 3183:

axis represents individual samples taken in between each transmit pulse. The

3131: 3123: 3108: 2997: 2767: 2755: 2727: 2598: 2577: 2534: 2495: 1642: 1604: 1006: 960: 742: 649: 405: 244: 127: 123: 6597: 5583:(Technical report). RADC Technical Reports. Vol. 1980. Rome, New York: 5449: 4779: 4098:

Hybrid mixers, fed by a waveform generator and an exciter for a complex but

793:

aircraft. Aircraft can land in fog at airports equipped with radar-assisted

7067: 6437: 4092: 3918: 3854: 3723: 3610: 3591: 3584: 3576: 3570: 3562: 2567: 2290: 1580:, which can be used to increase detection range and reduce transmit power. 1274: 1026: 837: 829: 805: 645: 611: 575: 508: 489: 477: 413: 225: 174: 111: 6143:

Secret Location: A witness to the Birth of Radar and its Postwar Influence

5929:". The Radar Pages. (History and details of various British radar systems) 5731: 5298: 1021:

travelling through one material meet another material, having a different

664:" for collecting reports of enemy aircraft and coordinating the response. 6967: 6781: 4530: 4457: 4246: 4147: 3969: 3624: 3450: 3365: 2921: 2920:

Mainlobe jamming can generally only be reduced by narrowing the mainlobe

2559: 2543: 1828:{\displaystyle F_{D}=2\times F_{T}\times \left({\frac {V_{R}}{C}}\right)} 1090: 901: 887: 556: 241: 138: 6645:

A set of educational videos created for air traffic control (ATC) staff.

5925: 5817:"Polyalphaolefins: A New Improved Cost Effective Aircraft Radar Coolant" 4563: 2668:

for each stage. The signal can also be split among multiple filters for

337:

tube for detecting distant lightning strikes. The next year, he added a

321:

showed that radio waves could be reflected from solid objects. In 1895,

282:

Other systems which are similar to radar make use of other parts of the

6545: 6462: 5967: 5030:"The history of radar, from aircraft radio detectors to airborne radar" 4511: 4361: 4151: 4072: 4026: 4022: 4013: 3848: 3141:

It is possible to make a Doppler radar without any pulsing, known as a

3112: 2861: 2797:(meteorological radars wish for the opposite effect, and therefore use 2763: 2747: 2735: 2731: 2708: 2634: 2581: 2573: 1618: 917: 905: 687: 653: 626: 441: 433: 378: 342: 115: 77: 6568: 6345:(Pages 36–67 contain the experiences of a WAAF radar plotter in WWII.) 2597:

clear sky, where the scene is so "cold" that it generates very little

2230:{\displaystyle |V_{R}|<{\frac {F_{R}\times {\frac {C}{F_{T}}}}{4}}} 228:

to locate landmarks and other ships, aircraft anti-collision systems,

6822: 6766: 6555:

Mark R. Bell (1993). "Information theory and radar waveform design".

5146:(Press release). The Patent Office. 10 September 2001. Archived from 5095: 4664:"Remote Sensing Core Curriculum: Radio Detection and Ranging (RADAR)" 4648: 4623: 4084: 3861:

as they combine good reception qualities with reasonable resolution.

3842: 3761: 3639: 3384: 3377: 3373: 3035: 3008: 2782: 2743: 2555: 1070: 1050: 948: 937: 853: 841: 598: 390: 382: 366: 330: 150: 60: 6575: 6526: 6443:

Waveform design for active sensing systems: a computational approach

4962:

Butement, W. A. S., and P. E. Pollard; "Coastal Defence Apparatus",

3352: 633: 6992: 6875: 6870: 6865: 6090:

A radar history of World War II: technical and military imperatives

4442: 4301: 4146:) was used in several military radars in the 1970s. However, it is 4140: 4136: 4130: 4103: 3486: 3455: 3391: 3369: 2910: 2299: 2276:

surface, such as rocks or soil, and are used by navigation radars.

1592: 1089:. These precautions do not totally eliminate reflection because of 925: 786: 529: 170: 107: 5672:

on 30 October 2021 – via YouTube; jaglavaksoldier's Channel.

5414:"Stopped Vehicle Detection (SVD) Comparison with Automotive Radar" 3071:

largely eliminating "noise" from the surfaces of bodies of water.

1657:

The Doppler frequency shift for active radar is as follows, where

6013:

Swords, Seán S., "Technical History of the Beginnings of Radar",

4120: 3986: 3931: 3922: 3914: 3607: 3154: 3135: 3111:

marks on the radar screen and then calculating the speed using a

3060: 2965: 2857: 2827:. Doppler separates clutter from aircraft and spacecraft using a 2273: 1911:{\displaystyle F_{D}=F_{T}\times \left({\frac {V_{R}}{C}}\right)} 833: 362: 334: 91: 82: 5471: 5037: 1001: 552:

successfully tested a primitive surface-to-surface radar to aim

275:

and are capable of extracting useful information from very high

267:

for geological observations. Modern high tech radar systems use

44: 6860: 6441: 6010:

Early development and production by Chrysler Corp. during WWII.

5942: 5542:

A Canadian Perspective on High-Frequency Over-the-Horizon Radar

4925:

History of Communications-Electronics in the United States Navy

4050: 4034: 3903: 3866: 3836: 3632: 3627:. The first fighter aircraft to use phased array radar was the 3498: 2869: 1290:(area) of the receiving antenna; this can also be expressed as 1062: 1034: 585: 404:

By placing a transmitter and receiver on opposite sides of the

5120:[New obstacle detection system and its applications]. 6725: 5972: 5726: 5118:"Nouveau système de repérage d'obstacles et ses applications" 4591:. Public Works and Government Services Canada. Archived from 4494: 4489: 4484: 4462: 4143: 3767: 3368:

that generates the radio signal with an oscillator such as a

3103: 3056: 1116:

returning to the receiving antenna is given by the equation:

621: 525: 464:, Anacostia, D. C., from the late 1930s (photo taken in 1945) 295: 287: 6178: 2814:

Moving target indication, which integrates successive pulses

2785:

between the radar transceiver and the antenna. In a typical

2512:

The maximum non-ambiguous range, which is determined by the

7062: 6613:

Mark A. Richards; James A. Scheer; William A. Holm (2010).

6460: 5926:

All you ever wanted to know about British air defence radar

5352:"These High-Tech Sensors May Be the Key to Autonomous Cars" 3064: 3408:

A display processor to produce signals for human readable

6531:. London: The Institution of Engineering and Technology. 6431: 6071:

RDF1: The Location of Aircraft by Radio Methods 1935–1945

5609:

Investigation of Terrain Bounce Electronic Countermeasure

4087:. They generate short pulses of power to feed, e.g., the 3812: 3781: 3234:

which prevents range from being determined directly, and

2992:

Distance may also be measured as a function of time. The

738:

that was used for many years in most radar applications.

607: 173:

use by several countries in the period before and during

6529:

Waveform design and diversity for advanced radar systems

6412: 6337:, Cardiff Centre for Lifelong Learning, Cardiff, 2009., 4872:"Making waves: Robert Watson-Watt, the pioneer of radar" 2758:

events. This phenomenon is especially apparent near the

955:

are also used in order to recover useful radar signals.

820:

and wind. It has become the primary tool for short-term

6527:

Fulvio Gini; Antonio De Maio; Lee Patton, eds. (2012).

6365:

Britain's shield: radar and the defeat of the Luftwaffe

6260:

The radar war: Germany's pioneering achievement 1904-45

6219: 4557:"Chapter I – Terminology and technical characteristics" 3587:. The amount of cancellation is side-lobe suppression. 3262:, moving target detection processors, correlation with 499:

In France in 1934, following systematic studies on the

5642:"Ground Surveillance Radars and Military Intelligence" 5256: 5254: 6947:

RIM-174 Standard Extended Range Active Missile (SM-6)

6238: 3565:: Not all radar antennas must rotate to scan the sky. 2996:

is the time it takes for a radar pulse to travel one

2650: 2310: 2268:

is used to minimize the interference caused by rain.

2164: 2134: 2074: 2040: 2013: 1986: 1959: 1932: 1856: 1767: 1744: 1717: 1690: 1663: 1461: 1351: 1297: 1125: 1005:

Brightness can indicate reflectivity as in this 1960

797:

systems in which the plane's position is observed on

637:

Memorial plaque commemorating Robert Watson-Watt and

6295: 6276: 4297: 3968:, meaning 'short'. Limited use due to absorption by 3831:, making them useful in the missile detection role. 3242: 3122:. Most modern radar systems use this principle into 201:

has since entered English and other languages as an

54:, used to track space objects and ballistic missiles 6489:

Signal Design for Active Sensing and Communications

5814: 5251: 5089: 3230:large dynamic range. Military applications require 5732:"Multi-function Phased Array Radar (MPAR) Project" 5497: 4739: 4586: 3282:processing are also used in clutter environments. 3164: 2823:The most effective clutter reduction technique is 2660: 2484:θe : elevation angle above the radar horizon 2467: 2229: 2147: 2117: 2053: 2026: 1999: 1972: 1945: 1910: 1827: 1750: 1730: 1703: 1676: 1562: 1357: 1331: 1243: 6314: 5247:. Bonnier Corporation. December 1941. p. 56. 3713:Institute of Electrical and Electronics Engineers 1332:{\displaystyle {G_{r}\lambda ^{2}} \over {4\pi }} 516:During the same period, Soviet military engineer 7080: 6179:Derek Howse; Naval Radar Trust (February 1993). 5577:A model for high frequency radar auroral clutter 5299:"The Wizard War: WW2 & The Origins of Radar" 5079:. Bonnier Corporation. October 1935. p. 29. 4740:Fakhrul Razi Ahmad, Zakuan; et al. (2018). 4725:: CS1 maint: bot: original URL status unknown ( 2781:Some clutter may also be caused by a long radar 2770:produces convection patterns in the ionospheric 2738:, animals (especially birds), turbulence in the 6639:MIT Video Course: Introduction to Radar Systems 6362: 6257: 6241:Principles of radar and sonar signal processing 6033:The radar army: winning the war of the airwaves 5534: 5532: 5268:. Hearst Magazines. September 1941. p. 26. 5212:"How the search for a 'death ray' led to radar" 5172:Improvements in or relating to wireless systems 5128:on 16 January 2009 – via radar-france.fr. 4996:. Hearst Magazines. December 1935. p. 844. 4767:Proc. of IEEE APS International Symposium 2001, 3722:Other users of the radio spectrum, such as the 1953:) is pulsed, using a pulse repeat frequency of 574:in Germany and then another in June 1935 by an 496:generated its radar technology during the war. 6813:Joint Tactical Information Distribution System 6687: 6485: 5686:. Applied Technology Institute. Archived from 5615:(Thesis). Wright-Patterson AFB, Dayton, Ohio: 4568:. International Telecommunications Union (ITU) 2929:to detect and disregard non-mainlobe signals. 6902:Space Tracking and Surveillance System (STSS) 6876:AN/SPY-6 Air and Missile Defense Radar (AMDR) 6673: 6159: 6106: 6068: 5990:Radar Navigation and Maneuvering Board Manual 5548:(Technical report). Ottawa, Ontario, Canada: 4990:"Radio Waves Warn Liner of Obstacles in Path" 3857:; 'L' for 'long'. Widely used for long range 2486:ha : height of the feedhorn above ground 2118:{\displaystyle |F_{D}|<{\frac {F_{R}}{2}}} 1403:= distance from the transmitter to the target 757:), and complementary navigation systems like 505:Compagnie générale de la télégraphie sans fil 6615:Principles of Modern Radar: Basic Principles 6554: 6388: 5529: 4964:Inventions Book of the Royal Engineers Board 4700:. Archived from the original on 2 March 2023 3285: 1053:substances, is used on military vehicles to 629:tower in Great Baddow, Essex, United Kingdom 197:for "radio detection and ranging". The term 6181:Radar at sea: the royal Navy in World War 2 6087: 5788: 5262:"Odd-shaped Boats Rescue British Engineers" 5182: 3387:that links the transmitter and the antenna. 3250:is employed in radar systems to reduce the 2774:. Radar clutter can degrade the ability of 2478: r : distance radar-target 1412:= distance from the target to the receiver. 7124:Science and technology during World War II 6680: 6666: 6220:Colin Latham; Anne Stobbs (January 1997). 6197: 6049: 5959:Introduction to Naval Weapons Engineering. 5564: 1388:, or scattering coefficient, of the target 6140: 5905:Learn how and when to remove this message 5124:(in French). 20 July 1934. Archived from 5110: 5062:, Doubleday Anchor, New York, 1962, p. 66 4772: 4647: 102:of objects relative to the site. It is a 27:Object detection system using radio waves 6277:Merrill Ivan Skolnik (1 December 1980). 6030: 6020:, Vol. 6, London: Peter Peregrinus, 1986 5952:The secret development of British radar. 5605: 5538: 5019:, vol. 2, no. 3 (Jul. 1972), pp. 241–263 4979:, Peter Peregrinus, Ltd, 1986, pp. 71–74 4977:tech. History of the Beginnings of Radar 4548: 3598:). They are the heart of the ship-borne 3575:Another method of steering is used in a 3557: 3534: 3470: 3432: 3418:A link to end user devices and displays. 3351: 3308:There are four common track algorithms. 3174: 3007: 2964: 2702: 2298: 1612: 1000: 928:, and wet ground. This makes the use of 881: 772: 681: 632: 620: 584: 455: 6557:IEEE Transactions on Information Theory 6548:MIMO radar: an idea whose time has come 5636: 5634: 5550:Defence Research and Development Canada 5524: 5495: 5321:"AIS vs Radar: Vessel Tracking Options" 5209: 4541: 4180:International Telecommunication Union's 3254:. Signal processing techniques include 3003: 2949: 2622:is bandwidth (post matched filter) and 2562:by at least the signal-to-noise ratio. 1104: 532:, entered into service in June 1943 on 14: 7081: 6803:Aegis Ballistic Missile Defense System 5570: 5504:. SciTech Publishing Inc. p. 98. 5296: 4937: 4918: 4382:Acronyms and abbreviations in avionics 4083:, and a high voltage switch such as a 3466: 2284: 671: 648:, Bawdsey Research Station located in 606:of 26 February 1935, using a powerful 451: 6661: 5552:. p. 38. DRDC Ottawa TM 2006-285 5349: 4474:Similar detection and ranging methods 3717:International Telecommunication Union 3179:Pulse-Doppler signal processing. The 732:Massachusetts Institute of Technology 472:, researchers in the United Kingdom, 6853: 6382: 5978:Penley, Bill, and Jonathan Penley, " 5861: 5666:"AN/PPS-5 Ground Surveillance Radar" 5631: 5606:Strasser, Nancy C. (December 1980). 5185:"Briefcase 'that changed the world'" 5176: 5083: 4780:"Christian Huelsmeyer, the inventor" 4277:Synthetically thinned aperture radar 3636:Passive electronically scanned array 3530: 3485:More modern systems use a steerable 3098: 3074: 2944: 2711:from a target cause ghosts to appear 886:3D Doppler radar spectrum showing a 816:Meteorologists use radar to monitor 522:Leningrad Electrotechnical Institute 312: 6897:Space-Based Infrared System (SBIRS) 6808:Active electronically scanned array 6413:Nadav Levanon; Eli Mozeson (2004). 5140:"British man first to patent radar" 4554: 3853:Long range air traffic control and 3643:Active electronically scanned array 3437:AS-3263/SPS-49(V) antenna (US Navy) 2558:requires a signal that exceeds the 2279: 317:As early as 1886, German physicist 24: 6907:Space Surveillance Telescope (SST) 6352:. Cardiff. Candy Jar Books. 2011. 5668:. 29 December 2009. Archived from 5539:Riddolls, Ryan J (December 2006). 5036:. 17 February 2015. Archived from 3681: 3447:omnidirectional broadcast antennas 616:Air Member for Supply and Research 25: 7155: 6942:RIM-161 Standard Missile 3 (SM-3) 6632: 6363:David Zimmerman (February 2001). 5728:National Severe Storms Laboratory 5617:Air Force Institute of Technology 5430:from the original on 9 June 2024. 5379:""AWACS: Nato's eyes in the sky"" 5350:Quain, John (26 September 2019). 5318: 4634:(3857): 391–392. 2 October 1943. 4222: 3422: 3251: 3243:Reduction of interference effects 2837:time-domain pulse-amplitude radar 1598: 589:The first workable unit built by 333:, developed an apparatus using a 169:Radar was developed secretly for 5935:Telephone History: Radar History 5866: 5684:"Fundamentals of Radar Tracking" 5092:"The story of RADAR Development" 4692: 4314: 4300: 3508: 3325:Interactive Multiple Model (IMM) 3210:accidents. Weather radar uses a 2601:. The thermal noise is given by 951:. More sophisticated methods of 106:method used to detect and track 59: 43: 6578:IEEE Signal Processing Magazine 6258:David Pritchard (August 1989). 5961:". (Radar fundamentals section) 5857: 5841: 5808: 5782: 5764: 5746: 5720: 5694: 5676: 5658: 5599: 5518: 5489: 5464: 5434: 5406: 5392: 5371: 5343: 5312: 5297:Goebel, Greg (1 January 2007). 5290: 5272: 5233: 5210:Harford, Tim (9 October 2017). 5203: 5183:Angela Hind (5 February 2007). 5154: 5132: 5065: 5052: 5022: 5009: 5000: 4982: 4969: 4956: 4931: 4912: 4903: 4878: 4864: 4838: 4816: 4803: 4790: 4216:radiolocation-satellite service 3825:ballistic missile early warning 3776:(OTH) radars; 'high frequency' 3553: 3376:and controls its duration by a 3260:Pulse-Doppler signal processing 3171:Pulse-Doppler signal processing 3165:Pulse-Doppler signal processing 3030:and is often found in aircraft 2954: 2686:Interference (wave propagation) 2679: 2670:pulse-Doppler signal processing 2244: 1839:Passive radar is applicable to 1578:pulse-Doppler radar performance 974: 877: 768: 460:Experimental radar antenna, US 408:in 1922, U.S. Navy researchers 7144:Wireless communication systems 7134:Radio stations and systems ITU 6881:Sea-based X-band Radar (SBX-1) 6471:. Cambridge University Press. 6446:. Cambridge University Press. 6417:. John Wiley & Sons, Inc. 6317:Introduction to airborne radar 6239:François Le Chevalier (2002). 5500:Introduction to Airborne Radar 4759: 4733: 4695:"History of Radar Meteorology" 4686: 4656: 4616: 4607: 4580: 4394:Amplitude-comparison monopulse 4162: 3880:ground controlled interception 3341: 3318:Probabilistic Data Association 3268:space-time adaptive processing 3026:This technique can be used in 2905:from the jammer to the radar ( 2808:in a clutter environment are: 2420: 2407: 2360: 2336: 2181: 2166: 2091: 2076: 1621:caused by motion of the source 1595:effects are also considered. 1534: 1525: 1198: 1189: 940:of the radio waves due to the 432:and P. E. Pollard developed a 389:before turning his inquiry to 325:, a physics instructor at the 13: 1: 6650:Glossary of radar terminology 6296:Merrill Ivan Skolnik (1990). 6279:Introduction to radar systems 6050:E.G. Bowen (1 January 1998). 5917: 5889:and help improve the section. 5241:"Night Watchmen of the Skies" 5073:"Mystery Ray Locates 'Enemy'" 4624:"Radio Detection and Ranging" 4210:, these might operate in the 4067: 2931:Other anti-jamming techniques 1926:When the transmit frequency ( 990: 872: 859:Intelligent Transport Systems 503:, the research branch of the 137:A radar system consists of a 7008:Mark 8 Fire Control Computer 7003:Mark I Fire Control Computer 6988:Comprehensive Display System 6741:Ship gun fire-control system 6300:. McGraw-Hill Professional. 6160:Peter S. Hall (March 1991). 6069:Michael Bragg (1 May 2002). 6018:History of Technology Series 5815:Stropki, Michael A. (1992). 5090:Alan Dower Blumlein (2002). 4367:Radar signal characteristics 3445:Early systems tended to use 3322:Multiple Hypothesis Tracking 3264:secondary surveillance radar 2494:of air, which is called the 1394:= pattern propagation factor 896:Radar signal characteristics 840:, precipitation types, etc. 520:, in collaboration with the 177:. A key development was the 7: 6243:. Artech House Publishers. 6202:. Wordsworth Editions Ltd. 5999:Radar – The Great Detective 5587:. p. 9. RADC-TR-80-122 5585:Rome Air Development Center 4942:. Springer. pp. 5–66. 4919:Howeth, Linwood S. (1963). 4587:Translation Bureau (2013). 4293: 4198:shall be classified by the 3715:and internationally by the 3647:Lockheed Martin F-22 Raptor 3313:Nearest neighbour algorithm 2883:Radar jamming and deception 2661:{\displaystyle {\sqrt {2}}} 1452:is the range. This yields: 1374:= gain of receiving antenna 1277:of the transmitting antenna 755:air-to-surface-vessel radar 747:aircraft interception radar 290:, which uses predominantly 80:to determine the distance ( 10: 7160: 6983:Naval Tactical Data System 6688:NATO naval weapons systems 6389:M I. Skolnik, ed. (1970). 6315:George W. Stimson (1998). 6198:R.V. Jones (August 1998). 6024: 5442:"The Technology Behind S+" 4333: 4327: 4200:radiocommunication service 4118: 4114: 3728:electronic countermeasures 3688:Radio spectrum § IEEE 3685: 3568: 3542: 3478: 3475:Surveillance radar antenna 3426: 3360:A radar's components are: 3345: 3289: 3252:radar interference effects 3236:range ambiguity resolution 3217:The alternate purpose is " 3168: 3078: 3015: 2977:(ranging) is based on the 2958: 2880: 2876: 2762:, where the action of the 2714: 2698: 2683: 2528: 2514:pulse repetition frequency 2288: 2248: 2128:Or when substituting with 1841:electronic countermeasures 1602: 994: 893: 848:to map the composition of 795:ground-controlled approach 694:A key development was the 690:radar operators in England 675: 548:. The following year, the 369:harbour but was rejected. 305: 301: 189:was coined in 1940 by the 29: 7058: 7032: 6955: 6919: 6889: 6846: 6790: 6749: 6721:Combat information center 6693: 6183:. Naval Institute Press. 4846:"gdr_zeichnungpatent.jpg" 4453:Radar engineering details 4399:Constant false alarm rate 4196:radiodetermination system 4192:radiodetermination system 3539:Slotted waveguide antenna 3348:Radar engineering details 3286:Plot and track extraction 3276:Constant false alarm rate 2843:Constant false alarm rate 2303:Echo heights above ground 2257:electromagnetic radiation 1645:, military aircraft, and 1633:Sea-based radar systems, 846:ground-penetrating radars 546:Naval Research Laboratory 462:Naval Research Laboratory 423:Naval Research Laboratory 269:digital signal processing 259:target locating systems, 207:losing all capitalization 7021:USN early guided weapons 6550:. IEEE Radar Conference. 6222:Radar: A Wartime Miracle 6111:. Simon & Schuster. 6092:. Taylor & Francis. 6054:. Taylor & Francis. 5948:12 December 2005 at the 5496:Stimson, George (1998). 4890:The Lemelson-MIT Program 4874:. BBC. 16 February 2017. 4404:Sensitivity time control 4272:Synthetic-aperture radar 3256:moving target indication 2644:can improve noise up to 2642:moving target indication 2524: 1738:is radial velocity, and 1635:semi-active radar homing 1628:moving target indication 1583:The equation above with 1365:= transmitted wavelength 1358:{\displaystyle \lambda } 1043:Radar absorbing material 799:precision approach radar 751:maritime patrol aircraft 728:MIT Radiation Laboratory 284:electromagnetic spectrum 265:ground-penetrating radar 6598:10.1109/MSP.2008.930414 6492:. Elanders Sverige AB. 6486:M. Soltanalian (2014). 6333:Younghusband, Eileen., 5791:"Physics of Outgassing" 5702:"Side-Lobe Suppression" 4668:University of Minnesota 4433:Crossed-field amplifier 4342:Terrain-following radar 3772:Coastal radar systems, 3706:over the horizon radars 3631:. The MiG-31M's SBI-16 3151:time-frequency analysis 2927:omnidirectional antenna 2833:moving target indicator 2806:measures of performance 2787:plan position indicator 2740:atmospheric circulation 2552:measures of performance 2482:ae : Earth radius 1758:is the speed of light: 1711:is transmit frequency, 1055:reduce radar reflection 1039:electrically conductive 922:electrical conductivity 488:, the Netherlands, the 395:Arnold Frederic Wilkins 387:radio direction finding 153:domain, a transmitting 7114:Navigational equipment 6932:RIM-67 Standard (SM-2) 6777:Close-in weapon system 6617:. SciTech Publishing. 6348:Younghusband, Eileen. 6319:. SciTech Publishing. 6107:Robert Buderi (1996). 5772:"Fully Coherent Radar" 4284:Over-the-horizon radar 4220: 4025:avoidance systems for 3823:Very long range (e.g. 3801:< 300 MHz 3676:airborne radar systems 3645:was introduced on the 3604:Patriot Missile System 3566: 3540: 3476: 3438: 3357: 3225:flying techniques and 3193: 3013: 2970: 2858:ionospheric reflection 2847:automatic gain control 2776:over-the-horizon radar 2712: 2662: 2500:curvature of the Earth 2487: 2469: 2295:Over-the-horizon radar 2231: 2149: 2119: 2055: 2028: 2001: 1974: 1947: 1912: 1829: 1752: 1732: 1705: 1684:is Doppler frequency, 1678: 1622: 1564: 1359: 1333: 1245: 1014: 924:—such as most metals, 891: 811:vessel traffic service 778: 720:attack on Pearl Harbor 691: 641: 630: 594: 465: 253:flight control systems 76:is a system that uses 32:Radar (disambiguation) 7109:Measuring instruments 7040:Ground-based systems: 6973:Torpedo Data Computer 6963:Radar in World War II 6164:. Potomac Books Inc. 6129:, McGraw Hill, 2005, 6073:. Twayne Publishers. 5704:. MIT. Archived from 5654:on 22 September 2010. 5058:Page, Robert Morris, 4938:Coales, J.F. (1995). 4886:"Robert Wattson-Watt" 4237:Continuous-wave radar 4212:radiolocation service 4188: 4184:ITU Radio Regulations 4127:travelling wave tubes 4081:pulse forming network 3735:Radar frequency bands 3561: 3538: 3474: 3436: 3355: 3280:digital terrain model 3178: 3143:continuous-wave radar 3028:continuous wave radar 3011: 2968: 2959:Further information: 2866:anomalous propagation 2795:circular polarization 2706: 2693:signal-to-noise ratio 2663: 2548:signal-to-noise ratio 2470: 2302: 2266:circular polarization 2249:Further information: 2232: 2150: 2148:{\displaystyle F_{D}} 2120: 2056: 2054:{\displaystyle F_{R}} 2029: 2027:{\displaystyle F_{R}} 2002: 2000:{\displaystyle F_{T}} 1975: 1973:{\displaystyle F_{R}} 1948: 1946:{\displaystyle F_{T}} 1913: 1830: 1753: 1733: 1731:{\displaystyle V_{R}} 1706: 1704:{\displaystyle F_{T}} 1679: 1677:{\displaystyle F_{D}} 1616: 1565: 1444:² can be replaced by 1360: 1334: 1246: 1019:electromagnetic waves 1004: 981:electromagnetic waves 949:electronic amplifiers 900:A radar system has a 894:Further information: 885: 863:detect human movement 776: 726:organized the secret 685: 678:Radar in World War II 636: 624: 588: 501:split-anode magnetron 459: 381:and the detection of 345:, he took note of an 339:spark-gap transmitter 327:Imperial Russian Navy 143:electromagnetic waves 7104:Microwave technology 7099:Aircraft instruments 6088:Louis Brown (1999). 6006:28 July 2020 at the 4542:Notes and references 4468:Travelling-wave tube 4157:Pollution Prevention 3972:at 22 GHz, so K 3859:early warning radars 3219:look-down/shoot-down 3153:(Weyl Heisenberg or 3088:early warning radars 3018:Frequency modulation 3004:Frequency modulation 2975:distance measurement 2973:One way to obtain a 2950:Distance measurement 2648: 2591:List of UWB channels 2308: 2251:Polarization (waves) 2162: 2132: 2072: 2038: 2011: 1984: 1957: 1930: 1854: 1765: 1742: 1715: 1688: 1661: 1459: 1349: 1294: 1123: 1105:Radar range equation 1027:diamagnetic constant 997:Reflection (physics) 852:. Police forces use 352:The German inventor 249:radar remote sensing 222:anti-missile systems 30:For other uses, see 7129:Targeting (warfare) 7119:Air traffic control 6998:Specific equipment: 6838:List of radar types 6818:Historical systems: 6798:Aegis Combat System 6716:Director (military) 6706:Fire-control system 6590:2009ISPM...26...32C 6461:Solomon W. Golomb; 5995:Wesley Stout, 1946 5981:Early Radar History 5965:Hollmann, Martin, " 5286:. 16 February 2017. 5060:The Origin of Radar 4921:"Ch. XXXVIII Radar" 4852:on 24 February 2015 4769:vol. 4. p. 44, 2003 4640:1943Natur.152..391. 4448:Omniview technology 4372:Pulse doppler radar 4330:List of radar types 3737: 3666:thinned array curse 3600:Aegis Combat System 3467:Parabolic reflector 3272:track-before-detect 3128:pulse-Doppler radar 2854:atmospheric ducting 2825:pulse-Doppler radar 2799:linear polarization 2778:to detect targets. 2531:Noise (electronics) 2285:Beam path and range 2270:Linear polarization 2007:with a distance of 1639:active radar homing 1609:Pulse-Doppler radar 1386:radar cross section 1264:= transmitter power 1237: 1222: 1099:radar cross section 1078:reflective surfaces 1067:Rayleigh scattering 1023:dielectric constant 822:weather forecasting 736:monopulse technique 672:During World War II 604:Daventry Experiment 452:Before World War II 399:General Post Office 354:Christian Hülsmeyer 218:air-defense systems 7050:Kerrison Predictor 6711:Fire-control radar 6367:. Sutton Pub Ltd. 6224:. Sutton Pub Ltd. 6141:Ian Goult (2011). 6127:Radar For Mariners 5943:WW2 Shadow Factory 5690:on 24 August 2011. 5357:The New York Times 5331:on 2 February 2019 5122:BREVET D'INVENTION 4589:"Radar definition" 4357:Inverse-square law 4308:Electronics portal 4262:Planar array radar 3804:> 1 m 3733: 3694:order of magnitude 3672:Aperture synthesis 3658:aperture synthesis 3567: 3541: 3477: 3439: 3358: 3227:stealth technology 3194: 3159:chirplet transform 3157:), as well as the 3051:available via the 3014: 2971: 2899:inverse-square law 2890:electronic warfare 2829:frequency spectrum 2752:geomagnetic storms 2713: 2658: 2631:Boltzmann constant 2550:are two different 2488: 2465: 2227: 2145: 2115: 2051: 2024: 1997: 1970: 1943: 1908: 1825: 1748: 1728: 1701: 1674: 1623: 1560: 1355: 1320: 1288:effective aperture 1241: 1223: 1208: 1015: 892: 779: 692: 642: 631: 595: 591:Robert Watson-Watt 582:in Great Britain. 580:Robert Watson-Watt 550:United States Army 466: 419:Lawrence A. Hyland 374:Robert Watson-Watt 234:space surveillance 230:ocean surveillance 191:United States Navy 128:weather formations 104:radiodetermination 7076: 7075: 7045:Gun data computer 6915: 6914: 6569:10.1109/18.259642 6499:978-91-554-9017-1 6453:978-1-107-01969-0 6383:Technical reading 6374:978-0-7509-1799-5 6358:978-0-9566826-2-8 6343:978-0-9561156-9-0 6326:978-1-891121-01-2 6307:978-0-07-057913-2 6288:978-0-07-066572-9 6269:978-1-85260-246-8 6262:. Harpercollins. 6250:978-1-58053-338-6 6231:978-0-7509-1643-1 6209:978-1-85326-699-7 6190:978-1-55750-704-4 6171:978-0-08-037711-7 6152:978-0-7524-5776-5 6145:. History Press. 6135:978-0-07-139867-1 6125:Burch, David F., 6118:978-0-684-81021-8 6099:978-0-7503-0659-1 6080:978-0-9531544-0-1 6061:978-0-7503-0586-0 6042:978-0-7090-4508-3 6031:Reg Batt (1991). 5968:Radar Family Tree 5915: 5914: 5907: 5789:J.L. de Segovia. 5754:"Radar Modulator" 5511:978-1-891121-01-2 5452:on 27 August 2016 5446:Sleep.mysplus.com 5421:Ogier Electronics 5266:Popular Mechanics 5216:BBC World Service 4994:Popular Mechanics 4949:978-1-349-13457-1 4693:Duda, Jeffrey D. 4595:on 4 January 2014 4565:Radio Regulations 4501:Historical radars 4480:Acoustic location 4288:Chirp transmitter 4108:pulse compression 4065: 4064: 3997:0.75–1.11 cm 3958:1.11–1.67 cm 3817:300–1000 MHz 3664:. Because of the 3596:Safeguard Program 3545:Slotted waveguide 3531:Slotted waveguide 3481:Parabolic antenna 3248:Signal processing 3199:spectrum analyzer 3099:Speed measurement 3081:Pulse compression 3075:Pulse compression 2945:Signal processing 2935:frequency hopping 2760:geomagnetic poles 2656: 2423: 2225: 2219: 2113: 2063:Nyquist frequency 1902: 1819: 1751:{\displaystyle C} 1555: 1329: 1239: 969:ultraviolet light 953:signal processing 867:gesture detection 824:and watching for 724:Alfred Lee Loomis 714:Popular Mechanics 658:Battle of Britain 544:, working at the 347:interference beat 313:First experiments 286:. One example is 261:self-driving cars 205:, a common noun, 50:Long-range radar 16:(Redirected from 7151: 7139:1940s neologisms 7025: 7019: 6937:MIM-104F (PAC-3) 6851: 6850: 6791:Specific systems 6682: 6675: 6668: 6659: 6658: 6628: 6624:978-1891121-52-4 6609: 6572: 6563:(5): 1578–1597. 6551: 6542: 6523: 6517: 6513: 6511: 6503: 6482: 6457: 6428: 6409: 6397: 6378: 6330: 6311: 6292: 6273: 6254: 6235: 6213: 6194: 6175: 6156: 6122: 6103: 6084: 6065: 6046: 5983:—an Introduction 5923:Barrett, Dick, " 5910: 5903: 5899: 5896: 5890: 5885:Please read the 5881:may need cleanup 5870: 5869: 5862: 5851: 5845: 5839: 5838: 5836: 5834: 5828: 5821: 5812: 5806: 5805: 5803: 5801: 5795: 5786: 5780: 5779: 5776:radartutorial.eu 5768: 5762: 5761: 5758:radartutorial.eu 5750: 5744: 5743: 5741: 5739: 5724: 5718: 5717: 5715: 5713: 5708:on 31 March 2012 5698: 5692: 5691: 5680: 5674: 5673: 5662: 5656: 5655: 5653: 5646: 5638: 5629: 5628: 5626: 5624: 5619:. pp. 1–104 5614: 5603: 5597: 5596: 5594: 5592: 5582: 5568: 5562: 5561: 5559: 5557: 5547: 5536: 5527: 5526: 5522: 5516: 5515: 5503: 5493: 5487: 5486: 5484: 5482: 5468: 5462: 5461: 5459: 5457: 5448:. Archived from 5438: 5432: 5431: 5429: 5418: 5410: 5404: 5403: 5396: 5390: 5389: 5383: 5375: 5369: 5368: 5366: 5364: 5347: 5341: 5340: 5338: 5336: 5327:. Archived from 5316: 5310: 5309: 5307: 5305: 5294: 5288: 5287: 5276: 5270: 5269: 5258: 5249: 5248: 5237: 5231: 5230: 5224: 5222: 5207: 5201: 5200: 5194: 5192: 5180: 5174: 5169: 5168: 5164: 5158: 5152: 5151: 5150:on 19 July 2006. 5136: 5130: 5129: 5114: 5108: 5107: 5105: 5103: 5094:. Archived from 5087: 5081: 5080: 5069: 5063: 5056: 5050: 5049: 5047: 5045: 5026: 5020: 5013: 5007: 5004: 4998: 4997: 4986: 4980: 4973: 4967: 4960: 4954: 4953: 4935: 4929: 4928: 4916: 4910: 4907: 4901: 4900: 4898: 4896: 4882: 4876: 4875: 4868: 4862: 4861: 4859: 4857: 4848:. Archived from 4842: 4836: 4831: 4830: 4826: 4820: 4814: 4807: 4801: 4794: 4788: 4787: 4776: 4770: 4763: 4757: 4756: 4754: 4752: 4737: 4731: 4730: 4724: 4716: 4707: 4705: 4699: 4690: 4684: 4683: 4681: 4679: 4670:. Archived from 4660: 4654: 4653: 4651: 4649:10.1038/152391b0 4620: 4614: 4611: 4605: 4604: 4602: 4600: 4584: 4578: 4577: 4575: 4573: 4561: 4552: 4526:Hohentwiel radar 4438:Gallium arsenide 4428:Cavity magnetron 4352:Radar navigation 4324: 4322:Geography portal 4319: 4318: 4317: 4310: 4305: 4304: 4174:) is defined by 3942:1.67–2.5 cm 3911:2.5–3.75 cm 3895:3.75–7.5 cm 3829:nuclear blackout 3774:over-the-horizon 3747:Wavelength range 3738: 3732: 3524:Conical scanning 3356:Radar components 3239:identification. 3223:nap-of-the-earth 3048:modulation index 3032:radar altimeters 2915:sidelobe jamming 2907:mainlobe jamming 2707:Radar multipath 2667: 2665: 2664: 2659: 2657: 2652: 2618:is temperature, 2492:refractive index 2474: 2472: 2471: 2466: 2464: 2463: 2451: 2450: 2441: 2440: 2428: 2424: 2419: 2418: 2397: 2396: 2387: 2386: 2368: 2367: 2358: 2357: 2348: 2347: 2332: 2331: 2322: 2280:Limiting factors 2236: 2234: 2233: 2228: 2226: 2221: 2220: 2218: 2217: 2205: 2200: 2199: 2189: 2184: 2179: 2178: 2169: 2154: 2152: 2151: 2146: 2144: 2143: 2124: 2122: 2121: 2116: 2114: 2109: 2108: 2099: 2094: 2089: 2088: 2079: 2060: 2058: 2057: 2052: 2050: 2049: 2033: 2031: 2030: 2025: 2023: 2022: 2006: 2004: 2003: 1998: 1996: 1995: 1979: 1977: 1976: 1971: 1969: 1968: 1952: 1950: 1949: 1944: 1942: 1941: 1917: 1915: 1914: 1909: 1907: 1903: 1898: 1897: 1888: 1879: 1878: 1866: 1865: 1834: 1832: 1831: 1826: 1824: 1820: 1815: 1814: 1805: 1796: 1795: 1777: 1776: 1757: 1755: 1754: 1749: 1737: 1735: 1734: 1729: 1727: 1726: 1710: 1708: 1707: 1702: 1700: 1699: 1683: 1681: 1680: 1675: 1673: 1672: 1569: 1567: 1566: 1561: 1556: 1554: 1553: 1552: 1543: 1542: 1537: 1521: 1520: 1519: 1507: 1506: 1497: 1496: 1487: 1486: 1476: 1471: 1470: 1364: 1362: 1361: 1356: 1338: 1336: 1335: 1330: 1328: 1319: 1318: 1317: 1308: 1307: 1296: 1250: 1248: 1247: 1242: 1240: 1238: 1236: 1231: 1221: 1216: 1207: 1206: 1201: 1185: 1184: 1183: 1171: 1170: 1161: 1160: 1151: 1150: 1140: 1135: 1134: 1087:stealth aircraft 1082:corner reflector 930:radar altimeters 844:use specialized 791:United Air Lines 763:RAF's Pathfinder 696:cavity magnetron 573: 470:Second World War 446:Chain Home (low) 308:History of radar 273:machine learning 251:, altimetry and 179:cavity magnetron 96:elevation angles 63: 47: 21: 7159: 7158: 7154: 7153: 7152: 7150: 7149: 7148: 7079: 7078: 7077: 7072: 7054: 7028: 7023: 7017: 6951: 6927:Harpoon missile 6911: 6885: 6842: 6786: 6762:Guided missiles 6757:Naval artillery 6745: 6689: 6686: 6655: 6635: 6625: 6539: 6515: 6514: 6505: 6504: 6500: 6479: 6454: 6425: 6406: 6398:. McGraw-Hill. 6395: 6385: 6375: 6350:One Woman's War 6327: 6308: 6289: 6281:. McGraw-Hill. 6270: 6251: 6232: 6210: 6200:Most Secret War 6191: 6172: 6153: 6119: 6100: 6081: 6062: 6043: 6027: 6008:Wayback Machine 5950:Wayback Machine 5920: 5911: 5900: 5894: 5891: 5884: 5877:Further reading 5871: 5867: 5860: 5855: 5854: 5846: 5842: 5832: 5830: 5826: 5819: 5813: 5809: 5799: 5797: 5793: 5787: 5783: 5770: 5769: 5765: 5752: 5751: 5747: 5737: 5735: 5725: 5721: 5711: 5709: 5700: 5699: 5695: 5682: 5681: 5677: 5664: 5663: 5659: 5651: 5644: 5640: 5639: 5632: 5622: 5620: 5612: 5604: 5600: 5590: 5588: 5580: 5569: 5565: 5555: 5553: 5545: 5537: 5530: 5523: 5519: 5512: 5494: 5490: 5480: 5478: 5476:Atap.google.com 5470: 5469: 5465: 5455: 5453: 5440: 5439: 5435: 5427: 5416: 5412: 5411: 5407: 5402:. 8 April 2019. 5398: 5397: 5393: 5381: 5377: 5376: 5372: 5362: 5360: 5348: 5344: 5334: 5332: 5317: 5313: 5303: 5301: 5295: 5291: 5278: 5277: 5273: 5260: 5259: 5252: 5245:Popular Science 5239: 5238: 5234: 5220: 5218: 5208: 5204: 5190: 5188: 5181: 5177: 5166: 5160: 5159: 5155: 5138: 5137: 5133: 5116: 5115: 5111: 5101: 5099: 5098:on 10 July 2011 5088: 5084: 5077:Popular Science 5071: 5070: 5066: 5057: 5053: 5043: 5041: 5040:on 20 June 2015 5028: 5027: 5023: 5017:Science Studies 5014: 5010: 5005: 5001: 4988: 4987: 4983: 4975:Swords, S. S.; 4974: 4970: 4961: 4957: 4950: 4936: 4932: 4917: 4913: 4908: 4904: 4894: 4892: 4884: 4883: 4879: 4870: 4869: 4865: 4855: 4853: 4844: 4843: 4839: 4834:Telemobiloscope 4828: 4822: 4821: 4817: 4808: 4804: 4795: 4791: 4778: 4777: 4773: 4764: 4760: 4750: 4748: 4738: 4734: 4718: 4717: 4710:Note: the word 4703: 4701: 4697: 4691: 4687: 4677: 4675: 4662: 4661: 4657: 4622: 4621: 4617: 4612: 4608: 4598: 4596: 4585: 4581: 4571: 4569: 4559: 4553: 4549: 4544: 4338: 4334:Main category: 4332: 4320: 4315: 4313: 4306: 4299: 4296: 4252:Monopulse radar 4225: 4208:secondary radar 4165: 4123: 4117: 4070: 4058:2.7–4.0 mm 4055:75–110 GHz 4042:4.0–7.5 mm 4019:Millimetre band 4009:40–300 GHz 3990: 3979: 3975: 3935: 3786:30–300 MHz 3744:Frequency range 3690: 3684: 3682:Frequency bands 3662:radio astronomy 3573: 3556: 3547: 3533: 3511: 3483: 3469: 3431: 3429:Antenna (radio) 3425: 3350: 3344: 3298: 3296:Track algorithm 3290:Main articles: 3288: 3245: 3173: 3167: 3101: 3083: 3077: 3020: 3006: 2963: 2957: 2952: 2947: 2885: 2879: 2766:on the earth’s 2719: 2717:Clutter (radar) 2701: 2688: 2682: 2651: 2649: 2646: 2645: 2635:Planck spectrum 2628: 2607: 2537: 2529:Main articles: 2527: 2485: 2483: 2481: 2479: 2477: 2475: 2459: 2455: 2446: 2442: 2436: 2432: 2414: 2410: 2392: 2388: 2382: 2378: 2363: 2359: 2353: 2349: 2343: 2339: 2327: 2323: 2321: 2317: 2309: 2306: 2305: 2304: 2297: 2287: 2282: 2253: 2247: 2213: 2209: 2204: 2195: 2191: 2190: 2188: 2180: 2174: 2170: 2165: 2163: 2160: 2159: 2139: 2135: 2133: 2130: 2129: 2104: 2100: 2098: 2090: 2084: 2080: 2075: 2073: 2070: 2069: 2045: 2041: 2039: 2036: 2035: 2018: 2014: 2012: 2009: 2008: 1991: 1987: 1985: 1982: 1981: 1964: 1960: 1958: 1955: 1954: 1937: 1933: 1931: 1928: 1927: 1893: 1889: 1887: 1883: 1874: 1870: 1861: 1857: 1855: 1852: 1851: 1845:radio astronomy 1810: 1806: 1804: 1800: 1791: 1787: 1772: 1768: 1766: 1763: 1762: 1743: 1740: 1739: 1722: 1718: 1716: 1713: 1712: 1695: 1691: 1689: 1686: 1685: 1668: 1664: 1662: 1659: 1658: 1647:radar astronomy 1611: 1603:Main articles: 1601: 1548: 1544: 1538: 1524: 1523: 1522: 1515: 1511: 1502: 1498: 1492: 1488: 1482: 1478: 1477: 1475: 1466: 1462: 1460: 1457: 1456: 1443: 1436: 1429: 1422: 1411: 1402: 1373: 1350: 1347: 1346: 1321: 1313: 1309: 1303: 1299: 1298: 1295: 1292: 1291: 1285: 1272: 1263: 1232: 1227: 1217: 1212: 1202: 1188: 1187: 1186: 1179: 1175: 1166: 1162: 1156: 1152: 1146: 1142: 1141: 1139: 1130: 1126: 1124: 1121: 1120: 1114: 1107: 999: 993: 977: 898: 880: 875: 771: 708:Popular Science 705:In April 1940, 680: 674: 567: 561:Rudolf Kühnhold 554:coastal battery 518:P.K. Oshchepkov 454: 438:Inventions Book 430:W.A.S. Butement 359:telemobiloscope 323:Alexander Popov 315: 310: 304: 232:systems, outer 214:radar astronomy 120:guided missiles 100:radial velocity 71: 70: 69: 68: 67: 64: 56: 55: 48: 35: 28: 23: 22: 15: 12: 11: 5: 7157: 7147: 7146: 7141: 7136: 7131: 7126: 7121: 7116: 7111: 7106: 7101: 7096: 7091: 7074: 7073: 7071: 7070: 7065: 7059: 7056: 7055: 7053: 7052: 7047: 7042: 7036: 7034: 7030: 7029: 7027: 7026: 7015: 7010: 7005: 7000: 6995: 6990: 6985: 6980: 6975: 6970: 6965: 6959: 6957: 6953: 6952: 6950: 6949: 6944: 6939: 6934: 6929: 6923: 6921: 6920:Naval missiles 6917: 6916: 6913: 6912: 6910: 6909: 6904: 6899: 6893: 6891: 6887: 6886: 6884: 6883: 6878: 6873: 6868: 6863: 6857: 6855: 6848: 6844: 6843: 6841: 6840: 6835: 6833:List of radars 6830: 6825: 6820: 6815: 6810: 6805: 6800: 6794: 6792: 6788: 6787: 6785: 6784: 6779: 6774: 6769: 6764: 6759: 6753: 6751: 6747: 6746: 6744: 6743: 6738: 6733: 6728: 6723: 6718: 6713: 6708: 6703: 6697: 6695: 6691: 6690: 6685: 6684: 6677: 6670: 6662: 6653: 6652: 6647: 6642: 6634: 6633:External links 6631: 6630: 6629: 6623: 6610: 6573: 6552: 6543: 6538:978-1849192651 6537: 6524: 6498: 6483: 6478:978-0521821049 6477: 6458: 6452: 6429: 6423: 6410: 6404: 6392:Radar Handbook 6384: 6381: 6380: 6379: 6373: 6360: 6346: 6331: 6325: 6312: 6306: 6298:Radar handbook 6293: 6287: 6274: 6268: 6255: 6249: 6236: 6230: 6217: 6214: 6208: 6195: 6189: 6176: 6170: 6157: 6151: 6138: 6123: 6117: 6104: 6098: 6085: 6079: 6066: 6060: 6047: 6041: 6026: 6023: 6022: 6021: 6011: 5993: 5986: 5976: 5963: 5953: 5939: 5930: 5919: 5916: 5913: 5912: 5874: 5872: 5865: 5859: 5856: 5853: 5852: 5840: 5829:on 5 June 2011 5807: 5781: 5763: 5745: 5719: 5693: 5675: 5657: 5630: 5598: 5574:(March 1980). 5563: 5528: 5517: 5510: 5488: 5472:"Project Soli" 5463: 5433: 5405: 5391: 5370: 5342: 5325:portvision.com 5319:Kline, Aaron. 5311: 5289: 5271: 5250: 5232: 5202: 5175: 5153: 5131: 5109: 5082: 5064: 5051: 5021: 5008: 4999: 4981: 4968: 4955: 4948: 4930: 4911: 4902: 4877: 4863: 4837: 4815: 4802: 4789: 4784:radarworld.org 4771: 4758: 4732: 4685: 4674:on 2 June 2021 4655: 4615: 4606: 4579: 4546: 4545: 4543: 4540: 4539: 4538: 4533: 4528: 4523: 4521:Würzburg radar 4518: 4516:Chain Home Low 4509: 4507:List of radars 4503: 4502: 4498: 4497: 4492: 4487: 4482: 4476: 4475: 4471: 4470: 4465: 4460: 4455: 4450: 4445: 4440: 4435: 4430: 4424: 4423: 4419: 4418: 4416:Proximity fuze 4412: 4411: 4407: 4406: 4401: 4396: 4390: 4389: 4385: 4384: 4379: 4377:Mmwave sensing 4374: 4369: 4364: 4359: 4354: 4349: 4344: 4328:Main listing: 4326: 4325: 4311: 4295: 4292: 4291: 4290: 4281: 4280: 4279: 4269: 4264: 4259: 4254: 4249: 4244: 4239: 4234: 4232:Bistatic radar 4224: 4223:Configurations 4221: 4164: 4161: 4119:Main article: 4116: 4113: 4112: 4111: 4096: 4069: 4066: 4063: 4062: 4059: 4056: 4053: 4047: 4046: 4043: 4040: 4039:40–75 GHz 4037: 4031: 4030: 4016: 4010: 4007: 4003: 4002: 3998: 3995: 3994:24–40 GHz 3992: 3988: 3983: 3982: 3977: 3973: 3959: 3956: 3955:18–24 GHz 3953: 3947: 3946: 3943: 3940: 3939:12–18 GHz 3937: 3933: 3928: 3927: 3912: 3909: 3906: 3900: 3899: 3896: 3893: 3890: 3884: 3883: 3875: 3874:7.5–15 cm 3872: 3869: 3863: 3862: 3851: 3845: 3839: 3833: 3832: 3821: 3818: 3815: 3809: 3808: 3805: 3802: 3799: 3795: 3794: 3790: 3787: 3784: 3778: 3777: 3770: 3764: 3758: 3752: 3751: 3748: 3745: 3742: 3702:radar equation 3686:Main article: 3683: 3680: 3654:interferometry 3629:Mikoyan MiG-31 3569:Main article: 3555: 3552: 3543:Main article: 3532: 3529: 3528: 3527: 3521: 3518: 3515: 3510: 3507: 3479:Main article: 3468: 3465: 3427:Main article: 3424: 3423:Antenna design 3421: 3420: 3419: 3416: 3413: 3410:output devices 3406: 3403:matched filter 3395: 3388: 3381: 3346:Main article: 3343: 3340: 3327: 3326: 3323: 3320: 3315: 3287: 3284: 3244: 3241: 3185:Range Interval 3169:Main article: 3166: 3163: 3120:Doppler effect 3100: 3097: 3079:Main article: 3076: 3073: 3041:beat frequency 3016:Main article: 3005: 3002: 2983:speed of light 2979:time-of-flight 2961:Time of flight 2956: 2953: 2951: 2948: 2946: 2943: 2881:Main article: 2878: 2875: 2821: 2820: 2819: 2818: 2815: 2715:Main article: 2700: 2697: 2684:Main article: 2681: 2678: 2655: 2626: 2605: 2587:ultra-wideband 2526: 2523: 2522: 2521: 2517: 2510: 2480:ke : 4/3 2462: 2458: 2454: 2449: 2445: 2439: 2435: 2431: 2427: 2422: 2417: 2413: 2409: 2406: 2403: 2400: 2395: 2391: 2385: 2381: 2377: 2374: 2371: 2366: 2362: 2356: 2352: 2346: 2342: 2338: 2335: 2330: 2326: 2320: 2316: 2313: 2286: 2283: 2281: 2278: 2246: 2243: 2238: 2237: 2224: 2216: 2212: 2208: 2203: 2198: 2194: 2187: 2183: 2177: 2173: 2168: 2142: 2138: 2126: 2125: 2112: 2107: 2103: 2097: 2093: 2087: 2083: 2078: 2048: 2044: 2021: 2017: 1994: 1990: 1967: 1963: 1940: 1936: 1920: 1919: 1906: 1901: 1896: 1892: 1886: 1882: 1877: 1873: 1869: 1864: 1860: 1837: 1836: 1823: 1818: 1813: 1809: 1803: 1799: 1794: 1790: 1786: 1783: 1780: 1775: 1771: 1747: 1725: 1721: 1698: 1694: 1671: 1667: 1600: 1599:Doppler effect 1597: 1571: 1570: 1559: 1551: 1547: 1541: 1536: 1533: 1530: 1527: 1518: 1514: 1510: 1505: 1501: 1495: 1491: 1485: 1481: 1474: 1469: 1465: 1441: 1434: 1427: 1420: 1414: 1413: 1409: 1404: 1400: 1395: 1389: 1378: 1377: 1376: 1375: 1371: 1366: 1354: 1341: 1340: 1327: 1324: 1316: 1312: 1306: 1302: 1283: 1278: 1270: 1265: 1261: 1252: 1251: 1235: 1230: 1226: 1220: 1215: 1211: 1205: 1200: 1197: 1194: 1191: 1182: 1178: 1174: 1169: 1165: 1159: 1155: 1149: 1145: 1138: 1133: 1129: 1112: 1106: 1103: 1049:and sometimes 1011:Hurricane Abby 995:Main article: 992: 989: 976: 973: 965:infrared light 942:Doppler effect 879: 876: 874: 871: 826:severe weather 770: 767: 743:night fighters 700:Tizard Mission 676:Main article: 673: 670: 662:Dowding system 639:Arnold Wilkins 542:Robert M. 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Hoyt Taylor 319:Heinrich Hertz 314: 311: 306:Main article: 303: 300: 292:infrared light 257:guided missile 242:meteorological 183:United Kingdom 124:motor vehicles 65: 58: 57: 49: 42: 41: 40: 39: 38: 26: 9: 6: 4: 3: 2: 7156: 7145: 7142: 7140: 7137: 7135: 7132: 7130: 7127: 7125: 7122: 7120: 7117: 7115: 7112: 7110: 7107: 7105: 7102: 7100: 7097: 7095: 7092: 7090: 7087: 7086: 7084: 7069: 7066: 7064: 7061: 7060: 7057: 7051: 7048: 7046: 7043: 7041: 7038: 7037: 7035: 7031: 7022: 7016: 7014: 7011: 7009: 7006: 7004: 7001: 6999: 6996: 6994: 6991: 6989: 6986: 6984: 6981: 6979: 6978:Ship systems: 6976: 6974: 6971: 6969: 6966: 6964: 6961: 6960: 6958: 6954: 6948: 6945: 6943: 6940: 6938: 6935: 6933: 6930: 6928: 6925: 6924: 6922: 6918: 6908: 6905: 6903: 6900: 6898: 6895: 6894: 6892: 6888: 6882: 6879: 6877: 6874: 6872: 6869: 6867: 6864: 6862: 6859: 6858: 6856: 6852: 6849: 6845: 6839: 6836: 6834: 6831: 6829: 6826: 6824: 6821: 6819: 6816: 6814: 6811: 6809: 6806: 6804: 6801: 6799: 6796: 6795: 6793: 6789: 6783: 6780: 6778: 6775: 6773: 6772:Depth charges 6770: 6768: 6765: 6763: 6760: 6758: 6755: 6754: 6752: 6748: 6742: 6739: 6737: 6734: 6732: 6729: 6727: 6724: 6722: 6719: 6717: 6714: 6712: 6709: 6707: 6704: 6702: 6701:Naval warfare 6699: 6698: 6696: 6692: 6683: 6678: 6676: 6671: 6669: 6664: 6663: 6660: 6656: 6651: 6648: 6646: 6643: 6640: 6637: 6636: 6626: 6620: 6616: 6611: 6607: 6603: 6599: 6595: 6591: 6587: 6583: 6579: 6574: 6570: 6566: 6562: 6558: 6553: 6549: 6544: 6540: 6534: 6530: 6525: 6521: 6509: 6501: 6495: 6491: 6490: 6484: 6480: 6474: 6470: 6469: 6464: 6459: 6455: 6449: 6445: 6444: 6439: 6435: 6430: 6426: 6424:9780471473787 6420: 6416: 6415:Radar signals 6411: 6407: 6405:0-07-057913-X 6401: 6394: 6393: 6387: 6386: 6376: 6370: 6366: 6361: 6359: 6355: 6351: 6347: 6344: 6340: 6336: 6332: 6328: 6322: 6318: 6313: 6309: 6303: 6299: 6294: 6290: 6284: 6280: 6275: 6271: 6265: 6261: 6256: 6252: 6246: 6242: 6237: 6233: 6227: 6223: 6218: 6215: 6211: 6205: 6201: 6196: 6192: 6186: 6182: 6177: 6173: 6167: 6163: 6158: 6154: 6148: 6144: 6139: 6136: 6132: 6128: 6124: 6120: 6114: 6110: 6105: 6101: 6095: 6091: 6086: 6082: 6076: 6072: 6067: 6063: 6057: 6053: 6048: 6044: 6038: 6034: 6029: 6028: 6019: 6017: 6012: 6009: 6005: 6002: 6000: 5994: 5991: 5987: 5984: 5982: 5977: 5974: 5970: 5969: 5964: 5962: 5960: 5954: 5951: 5947: 5944: 5940: 5937: 5936: 5931: 5928: 5927: 5922: 5921: 5909: 5906: 5898: 5895:November 2014 5888: 5887:editing guide 5882: 5878: 5873: 5864: 5863: 5850: 5849:radar / RADAR 5844: 5825: 5818: 5811: 5792: 5785: 5777: 5773: 5767: 5759: 5755: 5749: 5733: 5729: 5723: 5707: 5703: 5697: 5689: 5685: 5679: 5671: 5667: 5661: 5650: 5643: 5637: 5635: 5618: 5611: 5610: 5602: 5586: 5579: 5578: 5573: 5567: 5551: 5544: 5543: 5535: 5533: 5521: 5513: 5507: 5502: 5501: 5492: 5477: 5473: 5467: 5451: 5447: 5443: 5437: 5426: 5422: 5415: 5409: 5401: 5395: 5387: 5380: 5374: 5359: 5358: 5353: 5346: 5330: 5326: 5322: 5315: 5300: 5293: 5285: 5281: 5275: 5267: 5263: 5257: 5255: 5246: 5242: 5236: 5229: 5217: 5213: 5206: 5199: 5186: 5179: 5173: 5163: 5157: 5149: 5145: 5141: 5135: 5127: 5123: 5119: 5113: 5097: 5093: 5086: 5078: 5074: 5068: 5061: 5055: 5039: 5035: 5031: 5025: 5018: 5012: 5003: 4995: 4991: 4985: 4978: 4972: 4965: 4959: 4951: 4945: 4941: 4934: 4927:. Washington. 4926: 4922: 4915: 4906: 4891: 4887: 4881: 4873: 4867: 4851: 4847: 4841: 4835: 4825: 4819: 4813: 4812: 4806: 4800: 4799: 4793: 4785: 4781: 4775: 4768: 4762: 4747: 4743: 4736: 4728: 4722: 4715: 4713: 4696: 4689: 4673: 4669: 4665: 4659: 4650: 4645: 4641: 4637: 4633: 4629: 4625: 4619: 4610: 4594: 4590: 4583: 4567: 4566: 4558: 4551: 4547: 4537: 4536:SCR-270 radar 4534: 4532: 4529: 4527: 4524: 4522: 4519: 4517: 4513: 4510: 4508: 4505: 4504: 4500: 4499: 4496: 4493: 4491: 4488: 4486: 4483: 4481: 4478: 4477: 4473: 4472: 4469: 4466: 4464: 4461: 4459: 4456: 4454: 4451: 4449: 4446: 4444: 4441: 4439: 4436: 4434: 4431: 4429: 4426: 4425: 4421: 4420: 4417: 4414: 4413: 4409: 4408: 4405: 4402: 4400: 4397: 4395: 4392: 4391: 4387: 4386: 4383: 4380: 4378: 4375: 4373: 4370: 4368: 4365: 4363: 4360: 4358: 4355: 4353: 4350: 4348: 4347:Radar imaging 4345: 4343: 4340: 4339: 4337: 4331: 4323: 4312: 4309: 4303: 4298: 4289: 4285: 4282: 4278: 4275: 4274: 4273: 4270: 4268: 4267:Pulse-doppler 4265: 4263: 4260: 4258: 4257:Passive radar 4255: 4253: 4250: 4248: 4245: 4243: 4242:Doppler radar 4240: 4238: 4235: 4233: 4230: 4229: 4228: 4219: 4217: 4213: 4209: 4205: 4204:primary radar 4201: 4197: 4193: 4187: 4185: 4181: 4177: 4176:article 1.100 4173: 4169: 4160: 4158: 4153: 4150:, leading to 4149: 4145: 4142: 4138: 4134: 4132: 4128: 4122: 4109: 4105: 4101: 4097: 4094: 4090: 4086: 4082: 4078: 4077: 4076: 4074: 4060: 4057: 4054: 4052: 4049: 4048: 4044: 4041: 4038: 4036: 4033: 4032: 4028: 4024: 4020: 4017: 4015: 4012:1.0–7.5 4011: 4008: 4005: 4004: 3999: 3996: 3993: 3991: 3985: 3984: 3971: 3967: 3964: 3960: 3957: 3954: 3952: 3949: 3948: 3944: 3941: 3938: 3936: 3930: 3929: 3924: 3920: 3916: 3913: 3910: 3908:8–12 GHz 3907: 3905: 3902: 3901: 3897: 3894: 3891: 3889: 3886: 3885: 3881: 3876: 3873: 3870: 3868: 3865: 3864: 3860: 3856: 3852: 3850: 3846: 3844: 3840: 3838: 3835: 3834: 3830: 3826: 3822: 3819: 3816: 3814: 3811: 3810: 3806: 3803: 3800: 3797: 3796: 3791: 3788: 3785: 3783: 3780: 3779: 3775: 3771: 3769: 3765: 3763: 3759: 3757: 3754: 3753: 3749: 3746: 3743: 3740: 3739: 3736: 3731: 3729: 3725: 3720: 3718: 3714: 3709: 3707: 3703: 3697: 3695: 3689: 3679: 3677: 3673: 3669: 3667: 3663: 3659: 3655: 3652:Phased-array 3650: 3648: 3644: 3641: 3637: 3634: 3630: 3626: 3621: 3617: 3614: 3612: 3609: 3605: 3601: 3597: 3593: 3588: 3586: 3580: 3578: 3572: 3564: 3560: 3551: 3546: 3537: 3525: 3522: 3519: 3516: 3513: 3512: 3509:Types of scan 3506: 3503: 3502:Pulse-Doppler 3500: 3494: 3492: 3488: 3482: 3473: 3464: 3462: 3457: 3452: 3448: 3443: 3435: 3430: 3417: 3414: 3411: 3407: 3404: 3400: 3396: 3393: 3389: 3386: 3382: 3379: 3375: 3371: 3367: 3363: 3362: 3361: 3354: 3349: 3339: 3337: 3336:radar tracker 3331: 3324: 3321: 3319: 3316: 3314: 3311: 3310: 3309: 3306: 3302: 3297: 3293: 3292:Radar tracker 3283: 3281: 3277: 3273: 3269: 3265: 3261: 3257: 3253: 3249: 3240: 3237: 3233: 3228: 3224: 3220: 3215: 3213: 3208: 3207:weather radar 3203: 3200: 3191: 3186: 3182: 3177: 3172: 3162: 3160: 3156: 3152: 3146: 3144: 3139: 3137: 3133: 3132:weather radar 3129: 3125: 3124:Doppler radar 3121: 3116: 3114: 3110: 3109:grease pencil 3105: 3096: 3092: 3089: 3082: 3072: 3068: 3066: 3062: 3058: 3054: 3049: 3044: 3042: 3037: 3033: 3029: 3024: 3019: 3010: 3001: 2999: 2998:nautical mile 2995: 2990: 2986: 2984: 2980: 2976: 2967: 2962: 2942: 2940: 2936: 2932: 2928: 2923: 2918: 2916: 2912: 2908: 2904: 2903:line of sight 2900: 2894: 2891: 2884: 2874: 2871: 2867: 2863: 2859: 2855: 2850: 2848: 2844: 2840: 2838: 2834: 2830: 2826: 2816: 2813: 2812: 2811: 2810: 2809: 2807: 2802: 2800: 2796: 2790: 2788: 2784: 2779: 2777: 2773: 2769: 2768:magnetosphere 2765: 2761: 2757: 2756:space weather 2753: 2749: 2745: 2741: 2737: 2733: 2729: 2728:precipitation 2725: 2718: 2710: 2705: 2696: 2694: 2687: 2677: 2675: 2671: 2653: 2643: 2638: 2636: 2632: 2625: 2621: 2617: 2613: 2610: 2604: 2600: 2599:thermal noise 2594: 2592: 2588: 2583: 2579: 2578:flicker noise 2575: 2571: 2569: 2563: 2561: 2557: 2553: 2549: 2545: 2540: 2536: 2535:Noise (radio) 2532: 2518: 2515: 2511: 2508: 2507: 2506: 2503: 2501: 2497: 2496:radar horizon 2493: 2476:Where : 2460: 2456: 2452: 2447: 2443: 2437: 2433: 2429: 2425: 2415: 2411: 2404: 2401: 2398: 2393: 2389: 2383: 2379: 2375: 2372: 2369: 2364: 2354: 2350: 2344: 2340: 2333: 2328: 2324: 2318: 2314: 2311: 2301: 2296: 2292: 2277: 2275: 2271: 2267: 2262: 2258: 2252: 2242: 2222: 2214: 2210: 2206: 2201: 2196: 2192: 2185: 2175: 2171: 2158: 2157: 2156: 2140: 2136: 2110: 2105: 2101: 2095: 2085: 2081: 2068: 2067: 2066: 2064: 2061:, called the 2046: 2042: 2019: 2015: 1992: 1988: 1965: 1961: 1938: 1934: 1924: 1904: 1899: 1894: 1890: 1884: 1880: 1875: 1871: 1867: 1862: 1858: 1850: 1849: 1848: 1846: 1842: 1821: 1816: 1811: 1807: 1801: 1797: 1792: 1788: 1784: 1781: 1778: 1773: 1769: 1761: 1760: 1759: 1745: 1723: 1719: 1696: 1692: 1669: 1665: 1655: 1651: 1648: 1644: 1643:weather radar 1640: 1636: 1631: 1629: 1620: 1615: 1610: 1606: 1605:Doppler radar 1596: 1594: 1590: 1586: 1581: 1579: 1574: 1557: 1549: 1545: 1539: 1531: 1528: 1516: 1512: 1508: 1503: 1499: 1493: 1489: 1483: 1479: 1472: 1467: 1463: 1455: 1454: 1453: 1451: 1447: 1440: 1433: 1430:and the term 1426: 1419: 1408: 1405: 1399: 1396: 1393: 1390: 1387: 1383: 1380: 1379: 1370: 1367: 1352: 1345: 1344: 1343: 1342: 1325: 1322: 1314: 1310: 1304: 1300: 1289: 1282: 1279: 1276: 1269: 1266: 1260: 1257: 1256: 1255: 1233: 1228: 1224: 1218: 1213: 1209: 1203: 1195: 1192: 1180: 1176: 1172: 1167: 1163: 1157: 1153: 1147: 1143: 1136: 1131: 1127: 1119: 1118: 1117: 1115: 1102: 1100: 1096: 1092: 1088: 1083: 1079: 1074: 1072: 1068: 1064: 1058: 1056: 1052: 1048: 1045:, containing 1044: 1040: 1036: 1032: 1028: 1024: 1020: 1012: 1008: 1007:weather radar 1003: 998: 988: 986: 982: 972: 970: 966: 962: 961:visible light 956: 954: 950: 945: 943: 939: 935: 931: 927: 923: 919: 915: 911: 910:radar signals 907: 903: 897: 889: 884: 870: 868: 864: 860: 855: 851: 850:Earth's crust 847: 843: 839: 838:winter storms 835: 831: 830:thunderstorms 827: 823: 819: 818:precipitation 814: 812: 807: 806:Marine radars 803: 800: 796: 792: 788: 783: 775: 766: 764: 760: 756: 752: 748: 744: 739: 737: 733: 729: 725: 721: 716: 715: 710: 709: 703: 701: 697: 689: 684: 679: 669: 665: 663: 659: 655: 651: 650:Bawdsey Manor 647: 640: 635: 628: 623: 619: 617: 613: 609: 605: 600: 592: 587: 583: 581: 577: 571: 566: 563:and the firm 562: 558: 555: 551: 547: 543: 538: 535: 531: 527: 523: 519: 514: 512: 511: 506: 502: 497: 495: 491: 487: 483: 479: 475: 471: 463: 458: 449: 447: 443: 439: 435: 431: 426: 424: 420: 415: 411: 407: 406:Potomac River 402: 400: 396: 392: 388: 384: 380: 375: 370: 368: 364: 360: 355: 350: 348: 344: 340: 336: 332: 328: 324: 320: 309: 299: 297: 293: 289: 285: 280: 278: 274: 270: 266: 262: 258: 254: 250: 246: 245:precipitation 243: 239: 235: 231: 227: 226:marine radars 223: 219: 215: 210: 208: 204: 200: 196: 192: 188: 184: 180: 176: 172: 167: 164: 160: 156: 152: 148: 144: 140: 135: 133: 129: 125: 121: 117: 113: 109: 105: 101: 97: 93: 89: 85: 84: 79: 75: 62: 53: 46: 37: 33: 19: 7068:Naval combat 7039: 7024:}} 7018:{{ 7012: 6997: 6977: 6827: 6817: 6735: 6730: 6654: 6614: 6584:(1): 32–41. 6581: 6577: 6560: 6556: 6547: 6528: 6488: 6467: 6442: 6438:Petre Stoica 6414: 6391: 6364: 6349: 6334: 6316: 6297: 6278: 6259: 6240: 6221: 6199: 6180: 6161: 6142: 6126: 6108: 6089: 6070: 6051: 6032: 6014: 5998: 5989: 5979: 5966: 5958: 5933: 5924: 5901: 5892: 5880: 5858:Bibliography 5848: 5843: 5831:. Retrieved 5824:the original 5810: 5798:. Retrieved 5784: 5775: 5766: 5757: 5748: 5736:. Retrieved 5722: 5712:11 September 5710:. Retrieved 5706:the original 5696: 5688:the original 5678: 5670:the original 5660: 5649:the original 5621:. Retrieved 5608: 5601: 5589:. Retrieved 5576: 5566: 5554:. Retrieved 5541: 5520: 5499: 5491: 5479:. Retrieved 5475: 5466: 5454:. Retrieved 5450:the original 5445: 5436: 5420: 5408: 5394: 5385: 5373: 5361:. Retrieved 5355: 5345: 5333:. Retrieved 5329:the original 5324: 5314: 5302:. Retrieved 5292: 5284:Daily Record 5283: 5274: 5265: 5244: 5235: 5226: 5219:. Retrieved 5215: 5205: 5196: 5189:. Retrieved 5178: 5171: 5156: 5148:the original 5144:Media Centre 5143: 5134: 5126:the original 5121: 5112: 5100:. Retrieved 5096:the original 5085: 5076: 5067: 5059: 5054: 5042:. Retrieved 5038:the original 5033: 5024: 5016: 5011: 5002: 4993: 4984: 4976: 4971: 4963: 4958: 4939: 4933: 4924: 4914: 4905: 4893:. Retrieved 4889: 4880: 4866: 4854:. Retrieved 4850:the original 4840: 4833: 4818: 4810: 4805: 4797: 4792: 4783: 4774: 4766: 4761: 4749:. Retrieved 4745: 4735: 4711: 4709: 4702:. Retrieved 4688: 4676:. Retrieved 4672:the original 4667: 4658: 4631: 4627: 4618: 4609: 4597:. Retrieved 4593:the original 4582: 4570:. Retrieved 4564: 4555:ITU (2020). 4550: 4226: 4199: 4195: 4189: 4175: 4171: 4167: 4166: 4135: 4124: 4093:pulsed power 4071: 3970:water vapour 3965: 3919:marine radar 3892:4–8 GHz 3871:2–4 GHz 3855:surveillance 3734: 3724:broadcasting 3721: 3710: 3698: 3691: 3670: 3651: 3622: 3618: 3615: 3611:surveillance 3592:Mammut radar 3589: 3585:antenna gain 3581: 3577:phased array 3574: 3571:Phased array 3563:Phased array 3554:Phased array 3548: 3495: 3490: 3484: 3461:a small part 3451:right angles 3444: 3440: 3359: 3332: 3328: 3307: 3303: 3299: 3246: 3216: 3204: 3195: 3190:bed of nails 3189: 3184: 3181:Range Sample 3180: 3147: 3140: 3117: 3102: 3093: 3084: 3069: 3045: 3040: 3025: 3021: 2993: 2991: 2987: 2972: 2955:Transit time 2939:polarization 2919: 2914: 2906: 2895: 2886: 2851: 2845:, a form of 2841: 2822: 2803: 2791: 2780: 2720: 2689: 2680:Interference 2639: 2623: 2619: 2615: 2611: 2608: 2602: 2595: 2572: 2568:noise figure 2564: 2541: 2538: 2504: 2489: 2291:Beam forming 2261:polarization 2254: 2245:Polarization 2239: 2127: 1925: 1921: 1847:as follows: 1838: 1656: 1652: 1632: 1624: 1584: 1582: 1575: 1572: 1449: 1445: 1438: 1431: 1424: 1417: 1415: 1406: 1397: 1391: 1381: 1368: 1280: 1267: 1258: 1253: 1110: 1108: 1075: 1059: 1016: 985:illumination 984: 978: 975:Illumination 957: 946: 933: 909: 899: 878:Radar signal 815: 804: 784: 780: 769:Applications 761:used by the 740: 712: 706: 704: 693: 666: 646:Air Ministry 643: 612:Hugh Dowding 596: 593:and his team 578:team led by 576:Air Ministry 557:searchlights 539: 515: 509: 498: 490:Soviet Union 467: 437: 427: 414:Leo C. 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BBC News 4895:1 December 4599:8 November 4512:Chain Home 4362:Wave radar 4152:hydrolysis 4073:Modulators 4068:Modulators 4023:power line 3917:guidance, 3491:radar lock 3232:medium PRF 3113:slide rule 3091:antennas. 2994:radar mile 2862:refraction 2764:solar wind 2750:caused by 2748:ionosphere 2732:hail spike 2582:heterodyne 2574:Shot noise 2289:See also: 1619:wavelength 1617:Change of 1109:The power 1071:resonances 1009:image (of 991:Reflection 873:Principles 854:radar guns 842:Geologists 688:Chain Home 654:Chain Home 627:Chain Home 442:Chain Home 434:breadboard 379:ionosphere 343:Baltic Sea 329:school in 238:rendezvous 151:microwaves 141:producing 116:spacecraft 7013:Navboxes: 6823:Nike Zeus 6767:Torpedoes 6518:ignored ( 6508:cite book 5988:Pub 1310 5932:Buderi, " 5800:12 August 5221:9 October 5191:16 August 5162:GB 593017 4751:9 January 4531:H2S radar 4186:(RR) as: 4131:klystrons 4089:magnetron 4085:thyratron 3741:Band name 3640:AN/APG-77 3487:parabolic 3385:waveguide 3378:modulator 3374:magnetron 3266:targets, 3130:systems ( 3036:sine wave 2911:sidelobes 2783:waveguide 2754:or other 2674:coherence 2556:Detection 2430:− 2412:θ 2202:× 1881:× 1798:× 1785:× 1589:multipath 1532:π 1509:σ 1353:λ 1326:π 1311:λ 1196:π 1173:σ 1047:resistive 938:frequency 918:scattered 914:reflected 908:known as 834:tornadoes 599:death ray 513:in 1935. 510:Normandie 391:shortwave 383:lightning 372:In 1915, 367:Rotterdam 331:Kronstadt 240:systems, 203:anacronym 163:processor 88:direction 7094:Avionics 6871:AN/SPY-3 6866:AN/SPY-1 6606:16437755 6465:(2005). 6440:(2012). 6432:Hao He; 6004:Archived 5985:". 2002. 5946:Archived 5833:18 March 5425:Archived 5304:24 March 5044:28 April 5034:kret.com 4824:GB 13170 4721:cite web 4572:24 March 4443:Klystron 4422:Hardware 4294:See also 4141:silicate 4137:Coolanol 4104:klystron 4100:coherent 3602:and the 3456:rotating 3399:receiver 3392:duplexer 3370:klystron 2614:, where 1593:pathloss 1448:, where 1051:magnetic 1033:or in a 926:seawater 828:such as 787:aviation 530:Gneiss-2 279:levels. 171:military 159:receiver 108:aircraft 7033:Related 6890:Optical 6847:Sensors 6750:Weapons 6694:General 6586:Bibcode 6434:Jian Li 6025:General 5400:"Terma" 5388:. 2007. 4704:2 March 4636:Bibcode 4214:or the 4178:of the 4170:(also: 4121:Coolant 4115:Coolant 3923:airport 3915:Missile 3882:tasks. 3820:0.3–1 m 3766:10–100 3608:weather 3579:radar. 3212:low PRF 3155:wavelet 3136:azimuth 3061:MISTRAM 2877:Jamming 2864:(e.g., 2699:Clutter 2629:is the 2520:target. 2274:fractal 2255:In all 1339:, where 494:Hungary 478:Germany 421:at the 363:Cologne 335:coherer 302:History 195:acronym 181:in the 155:antenna 145:in the 132:terrain 98:), and 92:azimuth 83:ranging 52:antenna 6861:OPS-24 6828:Lists: 6621: 6604: 6535: 6496: 6475: 6450: 6421: 6402: 6371: 6356: 6341: 6323: 6304: 6285: 6266: 6247: 6228: 6206: 6187: 6168: 6149: 6133: 6115: 6096: 6077: 6058: 6039: 5955:ES310 5875:This " 5734:. 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