Sparse array aperture extension with dual-size spatial invariances for ESPRIT-based direction finding

A novel sparse array geometry embedding two sizes of spatial invariances is proposed for array aperture extension using a new ESPRIT-based algorithm. This novel direction finding method extends array aperture without additional antennas, irregular inter-element spacings, nor any cyclic ambiguity in the final arrival angle estimates. The half-wavelength invariance yields unambiguous but high-variance DOA estimates to disambiguate low-variance but cyclically ambiguous estimates obtained using the larger invariance. Under one simulation scenario with two close emitters, the proposed algorithm offers an astounding two orders of magnitude improvement in estimation standard deviation and bias and 50 dB reduction in resolution threshold, relative to a customary half-wavelength array of comparable hardware and software complexity. Any additional computation needed by this method may be performed in parallel, thereby requiring no serious increase in overall computational time.