SIW Cavity-Backed Self-Quadruplexing Antenna for Compact RF Front Ends

A compact quarter-mode substrate integrated wave-guide (QMSIW)-based self-quadruplexing antenna is proposed forcompact radio frequency (RF) front ends. The QMSIW-based self-quadruplexing antenna has four unequal resonators resonatingat the Industrial, Scientific, and Medical (ISM) band (2.45 GHz),fifth-generation (5G) band (3.5 GHz), wireless local area network(WLAN) band (4.9 GHz), and wireless fidelity band (5.4 GHz). Allfour resonators radiate through the open-ended wall of the QMSIWresonator and the arc-shaped slot inside the cavity. By properlyoptimizing the locations and dimensions of the resonators, higherisolation (>29.9 dB) is gained. In fact, all four resonators operateon a common grounded substrate with negligible interference. Adummy rectangular device is used to keep the printed circuit board(PCB) and antenna in it to measure theS-parameters and radiationproperties. The proposed antenna has a lower circuit size (0.23λ2g),reasonable gain (>3.85 dBi), high efficiency (>82.7 %), and highisolation (>29.9 dB). Based on the above-mentioned attributes, itis a good candidate for compact RF front ends.