Strategies for the calibration of an array of patch antennas in passive bistatic SAR imaging

One of the main challenges in opportunistic bistatic SAR imaging is the synchronisation of the receiver with the transmitter of opportunity. By adaptive spatial beamforming, we can retrieve the reference signal needed to perform the synchronisation in SAR imaging. This processing also attenuates the direct path interference. In this paper, a four-element patch array antenna is considered. In addition, this phased-array can be used to reject interferences coming from external sources. The calibration of the receiver is of utmost importance considering on the one hand the significant mutual coupling between the antenna elements and on the other hand the differences in phase and gain between the reception chains. This paper discusses two calibration strategies and compares their performance on experimental data.