Extended-aperture spatial diversity and polarizational diversity using a sparse array of electric dipoles or magnetic loops

A novel eigenstructure scheme of extended-aperture spatial diversity and polarizational diversity is proposed for 2D arrival angle estimation. This innovational method involves uniformly spaced triads (or pairs) of electric dipoles or magnetic loops, spaced much farther apart than a half-wavelength. An ESPRIT-based step produces arrival angle estimates that suffer cyclic ambiguity due to the extended spacing. Then, a closed-form integer search is performed over a MUSIC null spectrum for all finite number of possible direction cosines in the cyclic ambiguity using the aforementioned cyclically ambiguous estimates. This approach produces highly accurate, yet unambiguous, azimuth and elevation angle estimates. This novel method facilitates (1) multipath de-correlation (independent fading), (2) coherent summation of multipaths from the same source, and (3) down-link beamforming from the base-station to the mobile