Three-dimensional point spread function characterization of a radially displaced scatterer

Abstract

For synthetic aperture radar (SAR) systems utilizing a circular aperture for target recognition, it is important to know how a target's point spread function (PSF) behaves as a function of various radar functional parameters and target positional changes that may occur during data collection. The purpose of this research is characterizing the three dimensional (3D) point spread function (3D PSF) behavior of a radially displaced point scatterer for circular synthetic aperture radar (CSAR). For an automatic target recognition (ATR) systems requiring target identification with a high degree of confidence, CSAR processing represents a viable alternative given it can produce images with resolution less than a wavelength. With very large CSAR apertures (90°r; or more) three dimensional imaging is possible with a single phase center and a single pass. Using a backprojection image formation process, point target PSF responses are generated at various target locations at a given radar bandwidth, depression angle and full 360°r; CSAR apertures. Consistent with previous studies, the 3D PSF for a point target located at the image center is cone shaped and serves as the basis for comparing and characterizing the 3D PSFs for radially displaced scatterers. For radially displaced point target, simulated results show 3D PSF response is asymmetric and tends to become an elliptic shape.