Radar System Engineering

SEC. 3.16] CITIES 103
signal represents the superposition of reflections from the surface elements
located within a region bounded by bearnwidth and pulse length.
The individual targets, however, because of their low absorption and high
retrodirectivity, are more effective than the scatterers and irregularities
responsible for ground return and sea return.
N
FIG. 3,28.—The Kanto plain north of Tokyo. Wavelength = 3.2 cm, 3“ beam, altitude
10,000ft, radius28 nauticalmi. 35”59’?J.139°59’E.
In spite of the fluctuations of individual signals the average intensity
of the return from a city is sufficiently high to form a relatively stable
bright area on the screen. The shape of this area and the brightness of
particular sections remain sensitive to altitude and direction of approach,
but the whole group of signals is strong enough to give a reliable indication
under most circumstances.
The appearance of city signals of various sizes is illustrated in Fig.
3.28, a photograph obtained over the Kanto plain north of Tokyo. The