Compact QMSIW-Based Self-Diplexing Antenna with Enhanced Isolation for 5G n77/n79 Band Applications

In this paper, a quarter-mode substrate-integrated waveguide (QMSIW)-based self-diplexing antenna is presented for 5G wireless communication applications. The antenna achieves diplexing functionality through the incorporation of T-shaped and longitudinal slots on its top metallic surface. It operates at 4 GHz and 4.52 GHz, offering high port isolation > 36 dB and achieving gains of 4.72 dBi and 4.56 dBi at the respective ports. The integration of longitudinal slots enhances isolation, reducing mutual coupling between ports and ensuring efficient operation. Fabricated on a compact substrate, the antenna is designed with an electrical footprint of 0.04 ${\lambda _0}^2$, where λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> represents the free-space wavelength at the lowest resonant frequency. Optimized for operation in the n77 and n79 bands, the antenna is well-suited for 5G mobile networks, fixed wireless access, and industrial IoT applications. Its ability to support high-speed, low-latency communication makes it a strong candidate for next-generation wireless infrastructure, catering to the increasing demand for efficient and reliable 5G connectivity.