A Low-Profile Triple-Band Dual-Polarized SIW Cavity-Backed Slot Antenna with Differential Fed

This paper presents a triple-band dual-polarized substrate integrated waveguide (SIW) cavity-backed slot antenna featuring low-profile design and differential feeding probes. The antenna operates by exciting $\mathrm{TE}_{120}, \mathrm{TE}_{130}$, and TE<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">220</inf> modes to generate dual-polarized radiations in an efficient manner. Through the utilization of five cross slots, the antenna effectively radiates at three resonant frequencies (7.48, 10.72, and 11.57 GHz). By employing a differential feeding structure, the antenna achieves over 35 dB of isolation between its two ports, as well as cross-polarization levels below $\mathrm{- 2 0} \mathrm{d B}$ and gains of 6.08, 12.01, and 6.59 dBi at the respective resonant frequencies. Notably, the profile of the antenna is only $0.013 \lambda_{0}$ (the wavelength in free space at the lowest operating frequency), rendering it suitable for integration into compact front-end circuits.