A High Isolation, Low-Profile, Triple-Port SIW Based Annular Slot Antenna for Millimeter-Wave 5G MIMO Applications

This paper presents a compact, triple-port, millimeter-wave (mm-wave) substrate-integrated waveguide (SIW) based annular slot antenna. The presented antenna was fabricated on a single dielectric layer, 30mil TLY-5 substrate with a standard PCB process. Measurement results show that, the proposed antenna can achieve better than 30dB isolation between the ports at 28GHz, thanks to carefully tuned distances between the ports and $\sim 90\%$ radiation efficiency. Furthermore, it has 4.7dBi and 8dBi radiation gain at 28GHz for single-port and double-port excitation cases respectively. Because of its easy integration and the high isolation between the ports, the presented antenna can be a promising candidate to be used as a monostatic simultaneous transmit and receive (STAR) antenna. In addition, depending on application, it can also be directly adopted to a 5G phased array system in either transmitter or receiver, without requiring physical modification.