“…The received signal at point (x,y) is Figure 1. Geometry of Imaging System sr(x,y,f,t) = kIll O(x,y,z )exp(j2wf(t-t d »dx dy dz (2) n n n n n n object where O(x,y,z) is the object distribution function, n n n describing the object in terms of the reflection coefficients. In general, the object reflectivity is a function of the frequency of the illuminating wave, but this dependency when known can be taken care of and compensated for in the reconstruction process.…”