Closed-form direction finding and polarization estimation with arbitrarilyspaced electromagnetic vector-sensors at unknown locations

This paper introduces a new closed-form ESPRIT-based algorithm for multisou rce direction finding and polarization estimation with arbitrarily spaced e lectromagnetic vector-sensors whose three-dimensional (3-D) locations need not be known, The vector-sensor, already commercially available, consists o f six colocated but diversely polarized antennas separately measuring all s ix electromagnetic-held components of an incident wavefield, ESPRIT exploit s the nonspatial interrelations among the six unknown electromagnetic-field components of each source and produces from the measured data a set of eig envalues, from which the source's electromagnetic-field vector may be estim ated to within a complex scalar, Application of a vector cross-product oper ation to this ambiguous electromagnetic-field vector estimate produces an u nambiguous estimate of that source's normalized Poynting vector, which cont ains as its components the source's Cartesian direction cosines. Monte Carl o simulation results verify the efficacy and versatility of this innovative scheme. This novel method maybe considered as a simplification and a refin ement over Li's earlier work in 1993 [8].