Calibration of a digital phased array for polarimetric radar

When an active phased array is used for polarimetric radar applications, the system must be calibrated to reflect the fact that polarization of the transmitted and received fields is dependent on the scan angle. This paper discusses the challenges of polarimetric phased array calibration, and demonstrates these techniques using a linear array of eight S-band dual-polarized antennas connected to an active Digital Array Radar (DAR) prototype system. The ability to accurately measure polarimetric scattering matrices is demonstrated after using direct far-field measurements to compensate for polarization errors on receive and target reflection measurements to compensate for transmit polarization errors.