Inflight Antenna Pattern Measurement for Bistatic Synthetic Aperture Radar Systems

Precise inflight antenna pattern should be known for synthetic aperture radar (SAR), so that an image pixel intensity is directly expressed in terms of the mean surface backscatter coefficient. For bistatic SAR (BiSAR), in which the transmitter and receiver are mounted on separate platforms, conventional passive calibrators are not applicable any more. As such, an approach is described on how to determine the inflight antenna patterns for BiSAR systems in this letter. This technique is suitable for high-resolution SAR due to the very high dynamic range. More importantly, this technique uses signal encoding to decouple the transponder from the background, which greatly improve the measurement performance. Theoretical analysis and simulation results also demonstrate its validity.