A single polarized substrate integrated waveguide (SIW) cavity supported self-quadruplexing antenna, designed for 5G/6G IoT applications is proposed and prototyped. The model is backed by a rectangular substrate integrated waveguide (RSIW) cavity and features four resonating patches excited separately through four different 50Ω feed lines. The antenna center frequencies are obtained at 3.29 GHz, 4.47 GHz, 5.85 GHz, and 7.07 GHz. Additionally, the cavity is engineered with four sets of micro pockets beneath the patches which can be filled with different materials to offer frequency-agile response. The operating frequencies can be tuned over a wide range between 3.29 GHz and 8.4 GHz as per the required targets. The layout of the model is chosen meticulously to ensure all ports are co-polarized and isolation between any two is better than 32 dB. The proposed antenna design exhibits competitive performances with a compact size of 0.09 λg², Front-To-Back-Ratio (FTBR) above 17.83 dB and peak gain of 7.6 dBi. Importantly, all ports are single polarized for the first time in their class. The performance is validated by an equivalent circuit model and prototype characterization. The proposed antenna specifications and configurations well suit for future high-end applications like IoT/5G/6G/satellite communications.
Vaishali et al. (2026) studied this question.