Joint DOA and Polarization Estimation With Crossed-Dipole and Tripole Sensor Arrays

Electromagnetic vector sensor arrays can track both the polarization and direction of arrival (DOA) of the impinging signals. For linear crossed-dipole arrays, as shown by our analysis, due to inherent limitation of the structure, it can only track one DOA parameter and two polarization parameters. For full 4-D (two DOA, and two polarization parameters) estimation, we could extend the linear crossed-dipole array to the planar case. In this article, instead of extending the array geometry, we replace the crossed-dipoles by tripoles and construct a linear tripole array. Detailed proof shows that such a structure can estimate the 2-D DOA and 2-D polarization information effectively in general. A brief comparison between the planar crossed-dipole array and the linear tripole array is performed at last, showing that although the planar structure has a better performance, it is achieved at the cost of increased physical size.

I. Introduction

The joint estimation of direction of arrival (DOA) and polarization for signals based on electromagnetic (EM) vector sensor arrays has been widely studied in the past [1]–[21]. In [1], the EM vector sensor was first used to collect both electric and magnetic information of the impinging signals, where all six EM components are measured to identify the signals. So far, most of the studies are focused on the linear structure employing crossed-dipoles [2]–[4] and tripole sensors [5]–[8], where the general 2-D DOA model is simplified into 1-D by assuming that all the signals arrive from the same known azimuth angle . In [22] and [23], MUSIC algorithm was proposed to deal with the joint DOA () and polarization (, ) estimation problem by considering DOA (1-D) and 2-D together, where a 3-D peak search is required with a very high computational complexity. In [9], [10], [24]–[26], methods were developed so that the DOA and polarization can be estimated separately.