A NEW SYSTEM MODEL FOR RADAR POLARIMETERS

The validity of the 2 x 2 receive R and transmit T model for radar polarimeter systems, first proposed in [1], is questioned. The model is found to be invalid for many practical realizations of radar polarimeters. This can lead to significant errors in the calibration of polarimetric radar images. A new, more general model is put forward, which includes the system defects which cause the 2 x 2 model to break down. By measuring one simple parameter from a polarimetric active radar calibration (PARC), it is possible to transform the scattering matrix measurements made by a radar polarimeter to a format compatible with a 2 x 2 R and T matrix model. Alternatively, the PARC can be used to verify the validity of the 2 x 2 model for any polarimetric radar system. Recommendations for the use of PARC's in polarimetric calibration and to measure the orientation angle of the H-V coordinate system are also presented.