Biologically inspired coupled antenna array for direction of arrival estimation

We propose to design a small-size antenna array having high direction of arrival (DOA) estimation performance, inspired by the Ormia ochracea´s coupled ears. The female Ormia is able to locate male crickets´ call accurately, for reproduction purposes, despite the small distance between its ears compared with the incoming wavelength. This phenomenon has been explained by the mechanical coupling between the Ormia´s ears, modeled by a pair of differential equations. In this paper, we first solve the differential equations governing the Ormia ochracea´s ear response, and convert the response to the pre-specified radio frequencies. Using the converted response, we then implement the biologically inspired coupling as a multi-input multi-output filter on a uniform linear antenna array output. We derive the maximum likelihood estimates of source DOAs, and compute the corresponding Cramér-Rao bound on the DOA estimation error as a performance measure. We use Monte Carlo numerical examples to demonstrate the advantages of the coupling effect.