Azimuth Phase Center Adaptation on Transmit for High-Resolution Wide-Swath SAR Imaging

Abstract

Synthetic aperture radar (SAR) systems with multiple receive channels allow for high-resolution wide-swath imaging thus overcoming a fundamental limitation of conventional single-aperture SAR. By using multiple apertures in azimuth, additional samples are received for each transmitted pulse. This allows for a reduced pulse repetition frequency (PRF) thereby enabling a wider swath. However, a non-optimum PRF is associated with a non-uniform sample spacing in azimuth and needs to be compensated by a multi-channel reconstruction algorithm. For strong deviations from the optimum PRF, the inverse character of such an algorithm might result in a degraded performance. This can be overcome by an innovative advanced transmit antenna architecture which allows for a pulse-to-pulse shift of the phase center. Such an antenna enables the adaptive adjustment of the system�s phase center positions to the respective PRF, by this ensuring constant performance over a clearly extended PRF range. Especially in combination with conventional multi-channel processing strategies this technique represents the next step towards a fully active Multiple-Input Multiple-Output (MIMO) SAR and has a great potential for future systems.