Compact three-beam antenna based on SIW multi-aperture coupler for 5G applications

In this paper, a new three-beam antenna is proposed based on substrate integrated waveguide (SIW) for 5G applications in the frequency range of 28–32 GHz. The radiating element is an SIW slot array antenna, which is fed by a new beamforming network (BFN). The proposed BFN consists of only one 3 × 3 multi-aperture coupler (MAC) and a 3 × 3 phase shifter. Due to the use of fewer components, the proposed BFN has a simple and compact structure compared to the conventional Butler matrix BFN. First, a MAC feeding network is designed, and then a multi-beam slot array antenna is designed and optimized by HFSS software to realize three beams in the directions of 40°, 0°, and −40°. The return loss and isolation of all three ports of the antenna are better than 10 dB from 28 to 32 GHz. The measured gains of the antenna are from 8 to 10.2 dBi for different beams in the operating frequency band. The area of the proposed antenna is 53.6 × 15.8 mm2, which shows about 42% reduction in comparison to the similar reported three-beam antenna. The fabricated antenna has been tested, and there is good agreement between the measured and simulated results.