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

This paper introduces a novel closed-form ESPRIT-based algorithm for multi-source direction finding using arbitrarily spaced electromagnetic vector-sensors whose locations need not be known. The electromagnetic vector-sensor, already commercially available, consists of six co-located but diversely polarized antennas separately measuring all six electromagnetic-field components of an incident wavefield. In this novel algorithm, ESPRIT exploits the non-spatial inter-relations 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-held 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