Page 135 - Fundamentals of Radar Signal Processing

0
FIGURE 2.22 General behavior of σ with grazing angle for land clutter. (After
Long, 2001.)

(2.64)

where γ is a characteristic of the particular clutter type at the radar frequency
0
and polarization of interest. This model predicts that σ is maximum at normal
incidence and becomes vanishingly small as the grazing angle tends to zero.
0
However, it does not adequately reflect the degree of change in σ often
observed at near-normal or near-zero incidence angles, and additional models
are often used at these two extremes.
Various predictive models for σ as a function of important parameters
0
have been presented in the literature. One well-known example is the Georgia
Tech Research Institute (GTRI) model given by

(2.65)

where σ is the RMS surface roughness and the parameters A, B, C, and D
h
depend on the clutter type and radar frequency. Sample values for X band are
given in Table 2.6.