Circular and Linear Polarization Inverse Sar Imaging of Simple Deterministic Targets and Statistically Known Randomly Rough Surfaces Using Constant and Varying Illumination

Abstract

In order to study mechanisms of scattering and their relative contributions to SAR and inverse SAR images, a special measurement setup has been constructed in the University of Texas at Arlington bistatic anechoic measurement facility. This setup can be used to generate images in which: (1) the target is illuminated from a constant direction as the receiver is rotated in azimuth; and (2) the target is illuminated from various directions as the receiver is rotated in azimuth. Note that the latter relates closely to conventional and spotlight mode SAR in the case where the receiver and transmitter are collocated. The former is of considerable interest scientifically in that it allows one to map the effect of a spatially fixed set of induced currents and charges. In this presentation we will discuss the imaging system performance and compare images obtained using both approaches, for a variety of simple targets and the statistically known randomly rough surfaces reported previously [3]. Important and unique features of the special imaging setup are: (1) wide-bandwidth spiral antennas to achieve nearly constant beamwidth over frequency, and to reduce problems associated with polarization alignment; and (2) an antenna mount fastened to the pedestal with r.f. connection through a rotary joint.