These formulas do not take into account other factors influencing the RF signals propagation, for example, absorption, polarization, scattering, reflection, and diffraction, which are described below.Ĭell Phone Signal Underground Propagation? These formulas are used in our calculator. To get the total radio horizon d of the receiving and transmitting antennas (or effective communication range between the two antennas) their radio horizons are added: The distance d₂ from a receiving antenna to the horizon can be calculated using the same formulas. Therefore, we can rewrite the formula above as If we consider the effect of the atmosphere on the propagation of RF signals, the Earth’s radius and hence the radio horizon can be increased by the factor of 4/3 or about 33%. Because of the refractive effects of atmospheric layers with different temperatures under normal conditions, RF signals propagate not in straight lines they bend towards the Earth surface and can propagate over the horizon.
The equations above do not take into account the effect of the atmosphere on the propagation of VHF and UHF signals. Note that the dimensions of h, R and d must be in the same units (e.g. H₁ is the transmitting antenna height above the ground, For a perfect sphere without any mountains, the distance d₁ from a transmitting antenna to the horizon or the line of sight, or radio horizon, can be calculated from the Pythagorean theorem (see the picture above):
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