Radar Line of Sight
(radar horizon)
Figure 1: Radar Line of Sight
(radar horizon)
Figure 1: Radar Line of Sight
The electromagnetic waves follow the rules of the optics in higher frequencies (>100 MHz). All radar unit systems almost without exception work in this frequency domain. Well, therefore the wave fronts also propagate to quasi-optical rules.
The earth's curvature may prevent the radar seeing a target within the maximum range given by the radar range equation. Therefore results a „dead zone” for every radar system in which one targets can't be detected.
However in the earth's atmosphere, electromagnetic waves are generally bent or refracted downward. This reduces the „dead zone” but causes fault in the distance and height measuring simultaneous. In practice this is achieved by using a value of 8.5·106m for the effective earths radius instead of real 6.4·106m.