Design of Compact Shielded QMSIW Based Self-Diplexing Antenna for High-Isolation

A new shielded quarter-mode substrate integrated waveguide (S-QMSIW) based self-diplexing antenna (SDA) with excellent isolations is reported in this study. A slot is etched onto the top of the metal to achieve dual-band characteristics. In the full-wave EM simulator (HFSS), two orthogonal microstrip feed lines simulate the S-QMSIW resonator at two distinct frequencies (2 GHz and 4.35 GHz). A lumped circuit model is expected to be used to analyse the antenna structure. By carefully optimizing the antenna size, a good isolation of more than 36 dB between two input ports is obtained. To prove the proposed concept, a self-diplexing antenna based on S-QMSIW is developed, fabricated, and tested. The proposed antenna peak gains at 2 GHz and 4.35 GHz are 4 dBi and 4.5 dBi, respectively. In each band, the antenna front-to-back ratio is more than 18 dB. The proposed antenna circuit is extremely compact (
$0.06{\lambda_{g}}^{2}$
). The present antenna has a simple design, improved isolation, and a compact size as compared to previous designs, which meets the growing need for RF device simplification and integration.