Radar System Engineering

102 PROPERTIES OF RADAR TARGETS [SEC.316
best overland contrast for the brightest target highlights. In this
manner, the points yielding the brightest returns are presented over a
“base map” which shows the location of the aircraft and which participates
in any geometrical distortions of the radar presentation. Studies
of this type of presentation show that (1) the location of the brightest
N
Fm. 3.27.—Boston,M2ss.,~th “ three-tOm”presentation(Sec. 13.21). Wavelength =
3,2 cm, 3° beam, altitude 4000 ft, radius 5 nautical mi. 42”20’N. 71°05’W.
signals changes from instant to instant, and (2) the great majority of
these highlights cannot be identified with any particular prominent
structures in the city. These bright signals, therefore, must be accidental
strong reflections produced at random by favorable illumination
of particular surfaces and by constructive interference of reflections
from different surfaces within a signal pulse packet or target area.
“City return” is similar to ground return and sea return in that each