Demands on polarization purity in the measurement and imaging of distributed clutter

Attention is given to the criteria required for the reduction of error in polarized scattering parameter recovery from point and distributed targets. It is noted that the antenna polarization isolation criteria must be defined over the processed beamwidth, in order to insure that accurate cross-polarized backscatter measurements are made. Also, the cross-polarized backscattering coefficient is a function of the difference between like-polarized scattering cross section amplitudes and the phase difference between like-polarized scattering cross sections. It is shown that the induced depolarized cross section is nonexistent if the scattering coefficients are identical in both amplitude and phase. The overall cross polarized measurement error increases with antenna beam width.