SIW-Based Self-Quadruplexing Antenna for Microwave and mm-Wave Frequencies

A low-profile substrate integrated waveguide (SIW) cavity backed self-quadruplexing slot antenna supporting both microwave and millimeter (mm)-wave frequencies is proposed. Initially, a square SIW resonator is designed, and diagonally bisected into two half-mode resonators. A small portion of each section is assigned for mm-wave frequencies (28 and 30 GHz), and the remaining parts are adjusted to operate at microwave frequencies (4.8 GHz and 5.4 GHz). The microwave frequencies utilize the fundamental mode of the cavity and attain a maximum gain of 5.4 and 5.2 dBi at 4.8 and 5.4 GHz, respectively. The mm-wave resonators take advantage of higher order mode, resulting in a realized maximum gain of 8 and 8.7 dBi at 28 and 30 GHz. The simulated and measured results verified that at the mentioned frequencies, the reflection coefficients are below -20 dB, and the isolation among ports is better than 20 dB as well. Thus, it is asserted that the suggested antenna is a good candidate for fifth-generation (5G) communication systems utilizing sub-6 GHz and mm-wave bands. This can be considered as the first self-quadruplexing antenna designed for both microwave and mm-wave frequencies.