Measurements of surface waves radiated by a vertically polarized antenna over planar seawater at 5 MHz. comparison to planar Earth models
Résumé
High Frequency propagation over the surface of the Earth or sea is a relevant subject today, especially for High-Frequency Surface Wave Radars (HFSWR) over the horizon. In this paper, we present measurements of Electric field propagating over sea water in HF Band compared to K.A. Norton, R.W.P. King and G. Millington's theories, thanks to a reliable measurement setup. The transmitter antennas are located on the coast while the receiver antenna is installed on a boat which sails at constant azimuth. The Electric field measurements are carried out with a shielded loop antenna and we measured the field strength attenuation versus distance between the transmitter and the boat along a sea water path. In order to take into account the media change (the coast and the sea water), Millington's solution has been added to King's and Norton's theories with the planar Earth model. At 5 MHz over the sea water, the environment of propagation is an attractive feature for the trans-horizon radar application. Indeed, the attenuation along the path in the planar model is similar to the attenuation in free space but over the horizon. The measurements performed at 5 MHz and the calculations are in a good agreement. Keywords— HF band measurements, surface-wave propagation, ground-wave field, vertical electric dipole, planar Earth model.
Mots clés
sea water path
ground-wave field
seawater
transmitting antennas
loop antennas
radar antennas
receiving antennas
Earth
receiver antenna
planar seawater
HFSWR
R.W.P. King theory
trans-horizon radar
vertical electric dipole
free space attenuation
Surface waves
Sea surface
Antenna measurements
transmitter antennas
vertically polarized antenna
shielded loop antenna
K.A. Norton theory
antenna radiation patterns
surface wave measurements
HF radio propagation
planar model
surface-wave propagation
planar Earth model
sea water
HF band measurements
frequency 5 MHz
high frequency propagation
field strength attenuation
high-frequency surface wave radars
constant azimuth
Sea measurements
G. Millington theory
electric field measurements
planar Earth models
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