Overlapping Azimuth Channels for SAR Imaging --- Revisited

Abstract

Digital beamforming in combination with multiple azimuth channels (MACs) enable high azimuth resolution Synthetic Aperture Radar (SAR). In terms of the SAR trade space this comes at the expense of restricting the instrument Pulse Repetition Frequency (PRF) operation to values close to the uniform PRF values, determined by the ratio of total antenna length to platform velocity, or otherwise sacrificing, i.e., increasing the signal-to-noise ratio (SNR) or azimuth-ambiguity-to-signal ration (AASR). An approach, which has been investigated earlier, to change (increase) the uniform PRF while keeping the antenna length constant is to use overlapping azimuth channels. Here the analog RF output of individual azimuth antenna elements are assigned to two (or even more) digital channels. In this paper the impact of utilizing overlapping azimuth channels on the SAR instrument and performance parameters is analyzed. The aim is to establish a thorough understanding of the SAR trade space. A rigorous methodology is followed in developing close form expressions to describe the relevant performance parameters.