Joint 2D-DOA and Polarization Parameter Estimation with Sparsely Stretched L-shaped Polarization Sensitive Array

In order to reduce the serious mutual coupling effect across the elements of the existing collocated vector sensor array and further improve the parameter estimation accuracy, a Sparsely Stretched L-shaped Polarization Sensitive Array (SSL-PSA) is proposed, and a novel method for estimating the azimuth-elevation angles as well as polarization parameters is presented accordingly. Firstly, the signal model of SSL-PSA is established. Then, the SSL-PSA is divided into 6 subarrays, thus the ESPRIT algorithm can be utilized to estimate the Rotational Invariant Factors (RIFs). On this basis, a set of fine but ambiguous estimates and four sets of unambiguous coarse estimates of direction cosine are obtained by a series of mathematical operations. Then, four corresponding steering vectors can be reconstructed and the correct coarse direction-cosine estimation can be determined according to the orthogonality of the steering vector and the noise subspace. Finally, the estimates of Direction-Of-Arrival (DOA) and polarization parameter can be achieved by the existing disambiguate method. Compared to the existing polarization sensitive array consists of collocated vector sensor, the proposed one has no collocated configuration, which can reduce the mutual coupling effect. Additionally, the proposed method can also extend the spatial aperture and refine the direction-finding accuracy without adding any redundant antennas. Simulations are carried out to verify the effectiveness of the proposed method.