Optimum dual baseline SAR cross-track interferometry

Conventional SAR interferometers derive the surface height from an estimate of the phase difference between the SAR processed echoes received by two displaced phase centers. This paper introduces a maximum likelihood algorithm to process the SAR data from the three phase centers, which can be obtained from two antennas by switching the transmitter between the two. The accuracy of the new technique is derived and compared to the conventional one. It is shown that this new approach to SAR interferometry provides better accuracy, together with adaptivity to the look angle and possibly surface slope. Moreover it maintains the wide unambiguous height range corresponding to the shortest baseline.