Low-order multi-port arrays with reduced element spacing for digital beam-forming and direction-finding

Abstract

An array of three monopole elements with reduced element spacing of to is considered for application in digital beam forming and direction finding. The small element spacing introduces strong mutual coupling between the array elements, which affect the signal-to-noise-ratio performance of the array. A decoupling network can compensate for the mutual coupling effects so that simultaneous matching can be achieved at all the ports. This thesis discusses that decoupling can be achieved analytically for arrays with three or more elements and describes Kurodaa??s identities to realize the lumped elements of the derived decoupling network. Design procedures and equations are proposed. Experimental results have shown a close agreement with the theoretical predictions. The decoupled array has a bandwidth of 1% and a superdirective radiation pattern. This narrowband and superdirective antenna is applicable for frequency selectivity in digital beam forming and direction finding.