Spatio-polarimetric Correlations in Single-feed Diversely Polarized Arrays

It is known that the use of dual polarizations can enhance the performance of direction-ofarrival (DOA) estimation in array processing when the sources have different polarizations [1, 2]. Recently, polarization diversity has also found applications in nonstationary signal array processing problems [3]. In [4], the spatial and polarimetric correlation characteristics have been investigated for double-feed dual-polarized arrays (referred to as dualpolarized array hereafter), and their performance was compared to that of single-polarized arrays with twice the number of array sensors. In this paper, we use the spatial and polarimetric correlations to consider the performance of single-feed linear arrays consisting of alternating circularly polarized antennas (referred to as diversely polarized array hereafter) for DOA estimations of linearly polarized sources. The spatio-polarimetric correlation coefficients and the DOA estimation performances are compared to those of the double-feed dual-polarized arrays. It is shown that, while an diversely polarized array shows comparable spatial and polarimetric resolution when two sources have close spatial signatures, it may produce grating lobes in the spatio-polarimetric correlation coefficients and, subsequently, false spectrum estimations in DOA estimations. Such problem can be avoided by using smaller interelement spacing at the expense of array aperture reduction.