116:. The imperfect conductivity of the ground tilts the waves forward, dissipating energy into the ground. The long wavelengths of these signals allow them to diffract over the horizon, but this leads to further losses. Signal strength tends to fall exponentially with distance once the Earth's curvature is significant. Above about 10 kHz,
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of the band. High frequency over-the-horizon radar may use groundwave at moderate ranges but skywave at longer distances. Military communications in the very low and low frequency range uses ground wave, especially to reach ships and submarines, as groundwaves at these long wavelengths penetrate well below the sea surface.
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was the first author to accurately describe groundwave mathematically, deriving an equation for field strength over a flat earth. Van der Pol and
Bremmer published calculations for a spherical Earth from 1937 to 1939. Later work focused on paths with variable conductivity, the effects of terrain and
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during the day when skywave is absent, and can be useful at high frequencies at short ranges. Uses include navigation signals, low-frequency time signals, longwave radio, and AM radio. The increased effectiveness of groundwave at lower frequencies gives AM radio stations more coverage at the low end
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transmissions between 3 and 30 MHz have more modest groundwave range and groundwave is unimportant above 30 MHz. Surface conductivity affects the propagation of ground waves, with highly conductive surfaces such as sea water providing the best propagation, and dry ground and ice performing
168:, low frequencies and ground-wave propagation. To prevent interference with these services, amateur and experimental transmitters were restricted to the high frequencies (HF), felt to be useless since their ground-wave range was limited. Upon discovery of the other propagation modes possible at
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of the ionosphere forms and absorbs lower frequency energy. This prevents skywave propagation from being very effective on mediumwave frequencies in daylight hours. At night, when the D layer dissipates, mediumwave transmissions travel better by skywave. Ground waves
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of ground waves varies, reaching tens of meters at medium frequencies over dry ground and even more at lower frequencies. Propagation predictions thus require knowing the electrical properties of subsurface layers, which are best measured from groundwave attenuation.
298:. Naval Electrical Engineering Training, Module 10. Naval Education and Training Professional Development and Technology Center. September 1998. p. 2.16. NavEdTra 14182. Archived from
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frequencies, the advantages of HF for commercial and military purposes became apparent. Amateur experimentation was then confined to only authorized frequencies in the range.
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Ground wave is important for radio signals below 30 MHz, but is generally insignificant at higher frequencies where line-of-sight propagation dominates.
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and higher over water when seas are rough. Hills, mountains, urban areas, and forests can create areas of reduced signal strength. The
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41:. Ground waves propagate parallel to and adjacent to the surface of the Earth, and are capable covering long distances by
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but changes in the ground can cause variation in signal strength. Attenuation over land is lowest in the winter in
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Angulo I, Barclay L, Chernov Y, Deminco N, Fernández I, Gil U, Guerra D, Milsom J, Peña I, De la Vega D (2014).
164:, ground waves were used extensively. Early commercial and professional radio services relied exclusively on
53:, because ground waves in radio propagation are not confined to the surface. Groundwave contrasts with
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reflect off the ionosphere at night, which is known as skywave. During daylight hours, the lower
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radio communication is via groundwave propagation. Groundwave is also the primary mode for
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104:, below 3 MHz, travel efficiently as ground waves. As losses increase with frequency,
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waves travel well; horizontally polarized signals are heavily attenuated.
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As the distance increases, ground waves spread out according to the
318:"Propagation and excitation of surface waves in an absorbing layer"
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Introduction to Wave
Propagation, Transmission Lines, and Antennas
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communications all make use of it. Range depends on frequency and
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around the Earth's curvature. This radiation is also known as the
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Ling, R. T.; Scholler, J. D.; Ufimtsev, P. Ya. (1998).
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16:Radio wave propagating along the Earth's surface
189:objects on the ground, and computer modeling.
127:Groundwave signals are relatively immune to
120:helps bend waves downward. Only vertically
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72:broadcasting, navigation systems such as
19:For broader coverage of this topic, see
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261:International Telecommunications Union
325:Progress in Electromagnetics Research
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253:Handbook on Ground Wave Propagation
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323:. Northrop Grumman Corporation.
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348:from the original on 2022-10-09
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292:"Chapter 2: Ground Waves"
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1:
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57:that requires no medium, and
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377:Radio frequency propagation
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55:line-of-sight propagation
259:. Geneva, Switzerland:
82:non-directional beacons
49:, or more properly the
303:(PDF (archive zipped))
118:atmospheric refraction
37:traveling through the
61:via the ionosphere.
338:10.2528/PIER97071800
162:development of radio
90:ground conductivity
47:Norton surface wave
154:medium frequencies
133:temperate climates
114:inverse-square law
84:, and short-range
51:Norton ground wave
270:978-92-61-18661-6
137:penetration depth
33:that consists of
31:radio propagation
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100:Lower frequency
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193:Related terms
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350:. Retrieved
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274:. Retrieved
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216:tropospheric
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144:Applications
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78:time signals
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21:Surface wave
212:ionospheric
170:medium wave
109:the worst.
102:radio waves
43:diffracting
27:Ground wave
352:2018-05-10
222:References
174:short wave
331:: 49–91.
199:shortwave
166:long wave
122:polarized
371:Category
343:Archived
210:include
180:Modeling
96:Overview
70:longwave
35:currents
276:23 July
203:D layer
160:In the
59:skywave
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218:waves
208:do not
129:fading
346:(PDF)
321:(PDF)
257:(PDF)
148:Most
74:LORAN
39:earth
278:2024
265:ISBN
214:and
172:and
68:and
333:doi
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230:^
86:HF
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66:AM
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335::
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23:.
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