Impulse response function for ultra-wideband SAR
Paper in proceedings, 2014
A new impulse response function (IRF) for ultra-wideband synthetic-aperture radar (SAR) is derived based on an analytical Fourier transform pair. The latter corresponds in 2D frequency domain to a triangular area with con-stant amplitude, zero amplitude otherwise, which is used to model the SAR IRF. We show that the IRF reduces to a 2D sinc function for small aperture angles and that it is a good approximation for SAR up to about 10° of aperture angle. This IRF also generates the characteristic crossed sidelobe arms of ultra-wideband SAR from two rotated and interfering sinc functions. For aperture angles greater than about 10°, the IRF is constructed by su-perposition of adjacent triangles next to each other in frequency domain. The IRF for ultra-wideband SAR corresponding to an annulus sector is thus given by an infinite series of such triangular regions, but only a few terms are necessary for typical ultra-wideband SAR systems. About one term per 10° of aperture angle gives an accurate result.