Substrate-Integrated-Waveguide-Fed Wideband Filtering Antenna for Millimeter-Wave Applications

In this article, a wideband filtering antenna based on substrate integrated waveguide (SIW) structure for millimeter-wave (mm-wave) applications is proposed and studied. The proposed antenna is developed using multilayer printed circuit board (PCB) technology. It consists of an SIW feeding structure with a coupling slot, differential-fed L-shaped probes as well as radiating patches. Such architecture provides wide impedance bandwidth along with good filtering characteristic in the lower stopband. Simultaneously, by introducing a pair of open slots on the individual radiating patch as well as two shorting loops on top of the coupling slot, good filtering response in the upper stopbancl is obtained. The suppression level in the lower stopband is then further improved by introducing a pair of shorted stubs in the coupling slot region. The proposed filtering antenna features no extra filtering circuits, but has wide bandwidth as well as low profile. To verify the proposed structure and design philosophy, antenna array prototypes have been designed, fabricated, and measured. It achieves a 29% bandwidth from 23.5 to 31.5 GHz. Good agreement is achieved between simulated and experimental results. The proposed antenna array is particularly suitable to be applied in 5G (the fifth generation) mm-wave backhaul communications.