A Low-Profile 2-D Multibeam Multifeed Antenna Array With Millimeter-Wave Applications

In this communication, a uniplanar 2-D multibeam multifeed antenna array based on $4 \times 4$ substrate-integrated waveguide (SIW) Butler matrix (BM) is proposed. The four-feed series antenna subarray is designed to generate four beams in the xoz and yoz planes. The four-feed series antenna subarray is vertically interwoven in both the X- and Y-directions, forming a multifeed grid antenna array. Four $4 \times 4$ SIW BMs are beam-forming network (BFN) for the multifeed grid antenna array to achieve 2-D multibeam. The proposed 2-D multibeam antenna array features a single-layer configuration. With 16 beams fed by four sets of $4 \times 4$ BMs, the antenna array is capable of beam switching in both the elevation and azimuth directions. To validate the design, a prototype was fabricated and measured. Experimental results show a wideband −10-dB impedance bandwidth ranging from 58 to 64.5 GHz, with measured gains ranging from 18.2 to 20.4 dBi at 60 GHz. These measured results closely align with the simulation results. Consequently, the proposed antenna array is deemed suitable for 5G terminal applications.