A passive coupling matrix design for improved resolution small aperture direction finding

In this paper, we present an approach to design passive coupling matrix to overcome the performance limitation of direction finding using small aperture array. This approach is inspired by the sound localization acuity of a parasitic fly called Ormia ochracea. Motivated by the requirement from practical implementation that each element of the coupling matrix is realized as a passive analog phase shifter and attenuator in a similar fashion as that of conventional analog beamforming, in the proposed approach we confine the magnitude of each element to being no larger than 1. By taking the advantage of the coupling mechanism, this approach can design compact aperture antenna array yet with much improved direction finding performance. Furthermore, the proposed design is applicable to arbitrary array geometry. Numerical examples illustrate the effectiveness of the proposed approach and show a performance gain of 30 over the uncoupled array of the same aperture of 10 cm diameter at 40 MHz.