A 2 × 2 matrix comprising four signal amplitudes that characterizes the scattering from a target in terms of a polarization basis. The basis is defined by two orthogonal vectors, for example, horizontal and vertical or right and left circular. The diagonal terms are the amplitudes of the copolarized signals corresponding to the two transmitted polarizations, and the off-diagonal terms are the amplitudes of the cross- polarized signals. Each term carries a double subscript that denotes the transmitted and received polarization. Compare covariance matrix.