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

This paper introduces a new closed-form ESPRIT-based algorithm for multisource direction finding and polarization estimation with arbitrarily spaced electromagnetic vector-sensors whose three-dimensional (3-D) locations need not be known. The vector-sensor, already commercially available, consists of six colocated but diversely polarized antennas separately measuring all six electromagnetic-field components of an incident wavefield. ESPRIT exploits the nonspatial interrelations among the six unknown electromagnetic-field components of each source and produces from the measured data a set of eigenvalues, from which the source´s electromagnetic-field vector may be estimated to within a complex scalar. Application of a vector cross-product operation to this ambiguous electromagnetic-field vector estimate produces an unambiguous estimate of that source´s normalized Poynting vector, which contains as its components the source´s Cartesian direction cosines. Monte Carlo simulation results verify the efficacy and versatility of this innovative scheme. This novel method maybe considered as a simplification and a refinement over Li´s (1993) work