Coherent calibration techniques for multistatic SAR image formation

Through the coherent combining of apertures, a multistatic SAR can provide the capability to dramatically increase coverage rates over that of conventional monostatic SAR platforms, while also providing image resolution enhancement similar to that of an equivalent large aperture monostatic SAR. This coherent integration requires that all apertures in the multistatic system be calibrated in both amplitude and phase before combining. While some variance in the amplitude calibration between apertures is acceptable, it is critical that all of the apertures see a given pixel in the same physical location, and therefore accurate phase calibration between apertures is essential. In the work presented here the focus is on using measurements in conjunction with simulation, to develop an adequate calibration scheme. Initially the issue of the appropriate calibration target will be discussed, followed by a discussion of the calibration scheme including representative results.