A Low Axial Ratio and Multilayer Coupled Radiation Stacked Satellite-Borne Antenna with Elimination of Efficiency Transmission Zero

Stacked circularly polarized (CP) satellite-borne antennas face critical challenges, including efficiency transmission zeros (ETZ) or gain dips (GD) in the operating band and axial ratio (AR) degradation in the 45° plane. To overcome these limitations, we propose a low AR and multilayer coupled radiation stacked satellite-borne antenna that eliminates ETZ. By analyzing the antenna equivalent circuit model, we propose a resonant circuit (RC) suppression technique to eliminate ETZ through targeted suppression of non-radiating RC at continuous boundary regions. Additionally, we employ a cross-polarization suppression strategy, truncating the diagonal corners of the middle patch reduces cross-polarization components while incorporating transverse serrated structures (TSS), longitudinal serrated structures (LSS), and symmetric chamfers (SC) on the metal walls, thereby enhancing AR performance in the 45° plane. A novel multilayer coupled radiation technique is further introduced, where a loaded square ring (SR) enables dual-frequency radiation of the top patch (TP) through vertical and horizontal coupling paths, thereby broadening the operating bandwidth. Measurement results validate that the proposed antenna achieves ETZ-free operation across the full navigation band (1.15 – 1.65 GHz), with a peak gain > 5 dBic, a minimum AR < 1 dB, and an AR < 5 dB beamwidth exceeding 150° in all cross-sections.