Transformation of Dual-Polarized Radar Measurements to Arbitrary Polarization Bases

Abstract

A fully polarimetric radar system consists of an orthogonal dual-polarized transmission mode and a dual-channel receive mode that are typically set to be copolar and cross polar to the transmit state of polarization. The transmit polarization state is switched every pulse repetition time (PRT) between any two orthogonal stales. This paper presents an interpolation technique to construct time series of instantaneous scattering matrices (ISM) from fully polarimetric time series measurements obtained at every PRT from distributed scatterers. It is also shown theoretically that propagation effects need not be removed before transformation. The constructed series of ISMs are then transformed to other polarization bases. The resulting new ISMs are then used to calculate the radar parameters in the new basis. The suggested procedure is studied using data (collected at linear ±45° as well as horizontal and vertical polarization bases) from POLDIRAD, the dual-channel, polarimetric C-band radar operated by the German Aerospace Research Establishment.