Essential Information & explanations, latest texts & monographs on
Radio_horizon.
New Horizons from Multi-Wavelength Sky Surveys: Caoceedings of the 179th Symposium of the International Astronomical Union Held in Baltimore, Usa, Au by Brian J. McLean
New Horizons from Multi-Wavelength Sky Surveys (International Astronomical Union Symposia , Vol 179) by Brian J. McLean
Over-The-Horizon Radar (The Artech House Radar Library) by A. A. Kolosov
Ham Radio Horizons: The Book by Peter O'Dell
Eyes Beyond the Horizon by Eleanor Bowman
Radio horizon
In telecommunication, radio horizon is the locus of points at which direct rays from an antenna are tangential to the surface of the Earth. If the Earth were a perfect sphere and there were no atmospheric anomalies, the radio horizon would be a circle. To compute the radius of the circle drawn on the earth in such a case use the formula:
Radio Horizon = 1.23 * sqrt(Antenna Height)
This is the straight line of sight horizon where Antenna Height is in feet and the Radio Horizon is in miles. The equivalent formula for an antenna height in metres and a radio horizon in kilometres would be
RH = 3.56 * sqrt(antenna height).
Note 1: The radio horizon of the transmitting and receiving antennas can be added together to increase the effective communication range.
Note 2: Antenna Heights above 1 million feet (1966 miles - 3157 kilometres) will cover the entire hemisphere and not increase the radio horizon.
VHF and UHF radio signals will bend slightly toward the earth's surface. This bending effectively increases the radio horizon and therefore slightly increases the formula constant. The ARRL Antenna Book gives a constant of 1.415 for weak signals during normal tropospheric conditions.
In practice, radio wave propagation is affected by atmospheric conditions, and the presence of obstructions, e.g., mountains and the effective radiated power from the transmitter.
References:
The above article is adapted from from Wikipedia All Wikipedia article text is available under the terms of the GNU Free Documentation License
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