Antenna-pattern correction for near-field-to-far field RCS transformation of 1D linear SAR measurements

In a previous AMTA paper [1], we presented a first-principles algorithm, called wavenumber migration (WM), for estimating a target's far-field RCS and/or far-field images from extreme near-field linear (one-dimensional) or planar (two-dimensional) SAR measurements, such as those collected for flight-line diagnostics of aircraft signatures. However, the algorithm assumes the radar antenna has a uniform, isotropic pattern for both transmitting and receiving. In this paper, we describe a modification to the (one-dimensional) linear SAR wavenumber migration algorithm that compensates for nonuniform antenna-pattern effects. We also introduce two variants to the algorithm that eliminate certain computational steps and lead to more efficient implementations. The effectiveness of the pattern compensation is demonstrated for all three versions of the algorithm in both the RCS and the image domains using simulated data from arrays of simple point scatterers.