Page 99 - Fundamentals of Radar Signal Processing

they are both illuminated (so that there is some backscatter) and within the

mainlobe of the antenna (so that their backscatter is not significantly attenuated).
Consequently, the effective downrange extent of the resolution cell is the lesser
of the range resolution and the elevation beamwidth as each is projected onto
the scattering surface. Depending on the relative values of range, range
resolution, and grazing angle, either could be the limiting factor. If the range
resolution limits the effective extent, the resolution cell is said to be pulse

limited; if the mainlobe extent is the limiting factor, it is said to be beam
limited. These two cases are shown in Fig. 2.3. The boundary between the two
cases is obtained by equating the pulse length and elevation beam extents as
projected onto the ground plane to see which is shorter: