SIW Cavity Backed Elliptical Patch Antenna with Wideband Characteristics for 5G Applications

In this paper, a new technique to design a compact substrate-integrated waveguide (SIW) cavity-backed antenna have been proposed. This technique utilizes a metallic feeding strip sandwiched between two layers of the same substrate and directly connected to the center conductor of the coaxial feed. Due to the incorporation of the metallic feeding strip, effective electrical path length increases, which shifts the operating frequency to a lower frequency range on a large scale. As a proof of concept, an elliptical cavity is designed by conceiving this new feeding mechanism that helps to shift the lower cut-off frequency from 32.97 GHz to 23.67 GHz without increasing the size of the cavity-backed antenna. Further, focal feed, slot-loading at two focal points, and incorporation of the metallic rod at the slot positions are also conceived to improve the radiation properties. A broad impedance bandwidth (IBW) ranging from 21.65 GHz to 31.49 GHz (37.03%) has been observed, with a peak gain of 4.86 dBi at 24.50 GHz. The design evolution and operation mechanism are discussed based on electromagnetic (EM) simulation results.