60 GHz 2-D Scanning Multibeam Cavity-Backed Patch Array Fed by Compact SIW Beamforming Network for 5G Applications

This paper presents a 2 × 2 multibeam array employing a novel wideband linearly polarized cavity-backed patch antenna for fifth-generation (5G) wireless communication technology. The antenna array comprises four layers stacked on top of one another. The proposed antenna element is composed of three substrate layers and excited using a substrate-integrated waveguide aperture-coupled feed. The antenna element exhibits -10 dB impedance bandwidth of 36.2% from 53 to 76.4 GHz with very flat gain and excellent radiation characteristics. A prototype is fabricated and tested. The compact 2-D scanning multibeam 2 × 2 antenna array is demonstrated at 60 GHz, where the proposed antenna element is utilized as a radiating element. By employing a novel compact beamforming network (BFN) in the design, the proposed array achieves a size reduction of more than 28% compared to an array fed with the conventional BFN, without degradation in the array performance. A wide bandwidth larger than 27% for |S
_11|
<; -10 dB and a peak gain of 12.4 dBi is achieved. The array shows a good symmetrical radiation pattern in the two perpendicular planes. Verified by prototype measurements, the proposed antenna element and multibeam array with features of a compact structure, low cost, wide bandwidth, and superior radiation performance would be practically attractive for 5G applications.