Monopulse based DOA and polarization estimation with polarization sensitive arrays

In this paper, the vector sensor array (VSA) and the scalar sensor array (SSA) with polarization sensitivity (PS) are placed under the same framework of polarization sensitive arrays (PSAs), whose direction-dependent PS factor is larger than zero. This commonality of their PS factors enables both VSA and SSA to perform polarization estimation effectively. Based on this new PSA model, a generalized monopulse algorithm is proposed to jointly estimate direction-of-arrival (DOA) and polarization parameters, by expanding the existing monopulse angle estimation in spatial domain to both spatial and polarization domains. Both the DOA and polarization parameters can be effectively and efficiently estimated by comparing the outputs of the sum and spatial/polarized difference beams with only one snapshot. Then, closed-form expressions for joint DOA and polarization estimation error variances are derived and the polarization estimation variance is proved to decrease monotonically with the PS factor. Simulations are carried out on an X-band 5 x 5 planar array composed of microstrip patch antennas to demonstrate the effectiveness of the proposed algorithm.