Radar System Engineering

98 PROPERTIES OF RA DAR TARGETS [six. 3.14
surface in terms of a small-scale relief model illuminated by a rotating
fan-shaped beam of light, with the source of light held above the model
at a height equivalent to the altitude of the aircraft. The direction
and shape of terrain shadows and the brightness of the near sides of the
mountains are properties of the radar picture which can readily be
understood through such scale models.
N
As an aircraft approaches a hill or mountain, it will evimtually (if
its altitude is greater than the height of the mountain) reach a position
where the farther slope is no longer hidden behind the crest. Although
the shadow is gone, it is still possible to distinguish the mountain on the
radar picture through the contrast between the brighter signal from the
near slope and the weaker signal from the far slope. In Fig. 3.24, for