Sidelobe Suppression Using the SVA Method for SAR Images and Sounding Radars

Abstract

The method of Spatially Variant Apodization (SVA) has been developed for eliminating and suppressing sidelobes in SAR images as far as possible while maintaining the original image resolution. In this paper, we investigate the applicability of SVA to E-SAR data acquired in standard side-looking geometry and for the first time to the nadir looking sounder mode. In contrast to usual SAR imagery, sounding radar data feature a very strong backscatter from nadir due to directly downlooking rather than slant-looking. The strong nadir echo corresponds to the air-ice interface directly below the aircraft. It causes accordingly severe sidelobes interfering neighboring pixels in the data such that snow or ice layers close to the surface usually cannot be detected. The paper describes the SVA implementation into SAR processing and concludes that SVA is capable to achieve a better image resolution in both kind of data, usual SAR imagery and sounding radar data, reducing the sidelobe level at the same time.