Effects of element cross-polarisation in adpative antennas

The response of an adaptive antenna with imperfectly polarized elements is calculated by extending the concept of pattern factors given by Colin and Zucker (1969) to the array case, whereby the factors become diagonal matrices. The diagonal elements of these matrices represent the array element responses, which need not be equal. It is shown that the cross-polarization response of the elements does not affect the residual interference-to-thermal noise ratio for single or coherent dual polarized interference sources. If an interference source is dual polarized with independent noise sources on each polarization, it will appear as two sources (requiring two degrees of freedom for complete cancellation) only if the two pattern matrices for the array are not related via a simple scalar constant. The effect of nonproportionality of the pattern factors in a real system is illustrated by simulating a Sampled Matrix Inversion array on a computer.