Aj. Weiss et B. Friedlander, MAXIMUM-LIKELIHOOD SIGNAL ESTIMATION FOR POLARIZATION-SENSITIVE ARRAYS, IEEE transactions on antennas and propagation, 41(7), 1993, pp. 918-925
We consider the problem of separating and estimating the waveforms of
superimposed signals received by a polarization-sensitive array. Signa
l estimation is accomplished by a two-step maximum likelihood procedur
e: (i) The directions of arrival and polarization parameters of all th
e signals are estimated. (ii) The estimated signal is obtained as a li
near combination of the array outputs, with weights which are computed
from the estimated direction/polarization parameters. The objective o
f this paper is to analyze the quality of the estimated signal in term
s of the output signal-to-interference ratio (SIR) and output signal-t
o-noise ratio (SNR). Closed-form expressions are derived for the outpu
t SIR and SNR of a general diversely polarized array. By evaluating th
ese expressions for selected test cases it is shown that polarization-
sensitive arrays can provide significantly higher output SIR and SNR t
han uniformly polarized arrays. The performance improvement is especia
lly significant for closely spaced sources with sufficiently different
polarization characteristics.