In-Band Scattering Reduction of Wideband Phased Antenna Arrays With Enhanced Coupling Based on Phase-Only Optimization Techniques

A novel systematic methodology based on phase-only optimization techniques is proposed for the realization of in-band scattering reduction of wideband phased antenna arrays with intentionally enhanced electromagnetic (EM) coupling. By only optimizing the phase excitation that can be implemented using a coaxial delay line at the feed port of each element, the array with lower monostatic scattering cross section (SCS) can be accomplished in the designated angular region with little degradation of radiation performances within the operating band. Based on fast and efficient synthesis expressions of scattering and radiation properties of the array with additional phase contributions, where all the mutual coupling effects are taken into account, and it is capable of realizing a systematic and fast optimization methodology of the phase excitations. Then, a joint optimization approach is adopted to achieve a balance between radiation and scattering characteristics of the array. A $1\times16$ linear array operating in 8-12 GHz for scanning up to ±60° is designed to validate the proposed approach. The simulated and measured results are in good agreement, indicating that the monostatic SCS of the optimal array is considerably reduced compared to that of the uniform array with equal phase excitations.