COMPACT SELF-QUADRUPLEXING ANTENNA BASED ON SIW CAVITY-BACKED WITH ENHANCED ISOLATION

A self-quadruplexing antenna based on substrate integrated waveguide (SIW) is presented. A slot is engraved on its top surface of the SIW cavity, which generates four different resonant frequencies (around 6.54, 7.64, 8.30, and 9.60 GHz) when it is excited by four 50 Ω microstrip feed lines. Also, each resonant frequency can be controlled independently. Due to a quarter mode (QM) cavity, the antenna size becomes compact. The measured results show that the isolation between any two ports is more than 32 dB, and the estimated gain is more than 7.8 dBi at the operating frequencies. The proposed design is simple to fabricate, compact, and easy to integrate with the planner circuits.