Calibration of Polarimetric Radars Using In-scene Reflectors

Abstract

A polarimetric radar calibration algorithm using three in-scene reflectors is developed based on the exact solution for general target choices. The transmitting and receiving ports of the polarimetric radar are modeled by two unknown polarization transfer matrices. These transfer matrices are solved in terms of measurements from three independent calibration targets with known scattering matrices. The solutions for several sets of calibration targets with simple scattering matrices are presented first. Then, when at least two of the target scattering matrices can be simultaneously diagonalized, polarimetric calibration is derived using the method of simultaneous diagonalization of two matrices. A transformation matrix is found to convert the general scattering matrices into the simple cases, and the problem is solved in the transformed domain. The solution to the original problem then can be expressed in terms of the solutions obtained for the simple scattering matrices. All possible combinations of calibration targets are discussed and the solutions are presented for the cases that at least two of the scattering matrices can be simultaneously diagonalized.