Resolution-Based Analysis for Optimizing Subaperture Measurements in Circular SAR Imaging

Abstract

Circular geometries are often encountered in nondestructive testing and evaluation applications. Circular synthetic aperture radar imaging technique, capable of producing high-resolution images, has great utility for this purpose. However, in many such applications, scanning only a portion of the circular geometry (i.e., scanning domain), called the subaperture, may only be possible or sufficient for a particular inspection need. Consequently, in subaperture imaging, for an imaging aspect angle and aspect angle measurement interval, we must determine the expected image resolution. In this paper, for an arbitrary area of interest, we analyze the image spatial resolution obtained from a generally defined aspect angle and aspect angle measurement interval. Using resolution as the criteria, we use this method to determine the boundary between small and large subapertures, which also show to produce markedly different range and cross-range resolutions as a function of aspect angle and aspect angle measurement interval. Moreover, the optimum aspect angle and aspect angle measurement interval for this fixed area of interest are defined based on these analyses. Finally, the results of these analyses and images obtained from simulations are compared and corroborated with relevant experimental results at X-band (8.2–12.4 GHz).