Polarimetric Passive Coherent Location

In this paper the exploitation of different linear polarimetric channels is considered as a way to mitigate the effect of interfering sources and to improve the target detection capability in an FM radio-based passive radar. The signals emitted on same/adjacent frequency channels by potential transmitters (other than the illuminator of opportunity) located in the surveillance area are shown to significantly affect the performance of the considered system in terms of both disturbance cancellation and target detection. Moreover, it is verified that the achievable performance is dependent on the adopted polarization at both the reference and the surveillance channel since employing vertically or horizontally polarized antennas might yield very different results. Therefore effective approaches are introduced to jointly exploit the diversity of information conveyed by different polarizations at both the reference and surveillance channels. The results are shown against a real data set collected by an experimental multichannel passive radar prototype developed and fielded at the DIET Dept. of the University of Rome "La Sapienza," Italy. A significant performance improvement is achieved with the proposed processing schemes that always provide better results than the standard processing of the signals collected at the best polarimetric reference and surveillance channels. Besides the expected improvement due to noncoherent integration of target echoes received on multiple channels, the proposed multipolarimetric operation is shown to yield a remarkable improvement when operating in a severe interference scenario so that it can be regarded as practical solution for robust and effective passive coherent location (PCL).