An Effective Optimization Methods for the Suppression of Edge Effects in Ultrawideband Tightly Coupled Antenna Arrays

An effective optimization method is proposed for the suppression of edge effects in finite ultrawideband tightly coupled antenna arrays (TCAAs). By designing a practical finite TCAAs, the influences of edge effects on active voltage standing wave ratio (VSWR) are analyzed. Meanwhile, both the active VSWR and the array gain pattern are formulated as analytical expressions with respect to amplitude and phase excitations for analyzing the design freedom of edge effects. Aimed at suppressing the edge effects within an ultrawideband operation band, a nonconvex optimization problem is established for the synthesis of tightly coupled dipole arrays (TCDAs), where array gains at considered scanning angles and frequencies satisfying given maximum active VSWR and amplitude dynamic range ratio (DRR) are maximized. The nonconvex problem is transformed into an iterative convex optimization problem by the use of an iterative way, and the amplitude and phase excitations are efficiently solved by the convex optimization algorithm accordingly. By comparing to the traditional uniform amplitude and progressive phase excitation (UAPPE) method, the simulated and measured results of the ultrawideband TCDA show that the proposed method can slightly improve array gains at most frequencies, while the active VSWRs are suppressed to 3 over a 10:1 bandwidth when scanning up to 45°.