Ultra-Low-Profile Decoupling Patch Structure for E-Plane Microstrip Antenna Arrays

An ultra-low-profile decoupling patch (DP) structure is proposed for E-plane microstrip antenna arrays. Without requiring ground modification or complex circuitry, the DP introduces a secondary coupling path that destructively interferes with surface wave coupling. Full-wave simulations and experimental results of a 1×4 array validate the design, showing isolation enhancement from −17 dB to −55 dB while preserving stable gain, high efficiency, and unaltered radiation patterns.