Page 108 - Fundamentals of Radar Signal Processing

echo is therefore proportional to RCS is proportional to the power of the

composite echo. Taking the squared magnitude of Eq. (2.47) and simplifying
leads to the result

(2.47)

(2.48)

Equation (2.48) shows that the RCS is a periodic function of both radar
frequency and aspect angle. The larger the scatterer separation in terms of
wavelengths, the more rapidly the RCS varies with angle or frequency. An exact

calculation of the variation in RCS of the dumbbell target is plotted in Fig. 2.6
for the case D = 10λ and R = 10,000D. The plot has been normalized so that the
maximum value corresponds to 0 dB. Notice the multilobed structure as the
varying path lengths traversed by the echoes from the two scatterers cause their
echoes to shift between constructive and destructive interference. Also note that
the maxima at aspect angles of 90° and 270° (the two “end fire” cases) are the

broadest, while the maxima at the two “broadside” cases of 0° and 180° are the
narrowest. Figure 2.7 plots the same data in a more traditional polar format.