Direction and polarization estimation using quaternion and polarization rotation matrix

Estimation of directions-of-arrival (DOAs) and polarization parameters of incident signals needs a high-dimensional searching process with long-vector methods, which results in tremendous computational load. To overcome this disadvantage, this paper proposes a novel algorithm using quaternion and polarization rotation matrix on the basis of a uniform circular array (UCA) which is composed of cocenterd orthogonal loop and dipole (COLD) pairs. First, a quaternion mode is set and polarization parameters are separated from the array manifold. Then, DOA parameters are acquired using a two-dimensional searching process. Meanwhile, based on long-vector mode, a polarization rotation matrix is constructed, and closed-form estimation of polarization parameters is obtained. The presented algorithm has a large reduction in computational effort and an obvious improvement in precision for DOA estimation under low signal-to-noise (SNR) ratio. The effectiveness is confirmed through computer simulation.