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systems. It is shaped to send more radio energy in certain directions in order to smooth out the reception pattern of objects as their range changes in relation to the radar. The name refers to the fact that the amount of energy returned from a target drops off with the square of the cosecant of the
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To counteract this, the scanning antenna was re-aimed so that it was pointed almost directly forward, thereby sending most of the radar energy at low angles relative to the aircraft, thereby increasing the energy available at long range. This left the area directly under the aircraft receiving no
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The same basic concept soon found many roles. For ground-based radars, the same modification could be used to provide scanning at high angles above the station while still sending most of the energy towards low angles to detect aircraft at long range as they rose above the
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distance between the radar and the terrain is the cosecant of the angle between the fuselage and the target, and the energy falls off with the fourth root of that number. Without correction, this produced a display where the ground under the aircraft was very bright on the
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energy at all, so the upper lip of the reflector was bent to reflect a small amount of energy in that direction. This results in a more even display pattern.
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The opposite modification could also be used, bending the upper lip outward, with the same basic outcome.
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shows the cosecant squared pattern in the increased curvature of the upper lip of the reflector plate.
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275:"Microstrip patch antenna array with cosecant-squared radiation pattern profile"
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Kaboutari, Keivan; Zabihi, A.; Virdee, B.S.; Pilevari
Salmasi, Mostafa (2019).
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display, while the terrain at longer distances was almost invisible.
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The radar equation states that the signal received from an object,
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AEU - International
Journal of Electronics and Communications
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The concept originated as part of the development of the
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at further distances is much a weaker signal due to the
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Type of parabolic reflector used in some radar systems
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48:angle between the radar and the target.
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315:"Antenna with Cosecant Squared Pattern"
189:. If the goal is to produce a constant
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107:above the ground and slant range
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294:10.1016/j.aeue.2019.05.003
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