Beamforming steering implementation using substrate-integrated waveguide Butler matrix and slotted array antenna for 5G n257 band

Abstract

This paper introduces a method to realize beam switching by using a substrate-integrated waveguide (SIW) Butler matrix combined with a slot array antenna. The Butler matrix consists of two hybrid couplers, two crossovers, two −45-degree phase shifters, and two 0-degree phase shifters. The slot array antenna is a 4 × 2 array. The operating frequency band of the slot array antenna, where the reflection coefficient is below −10 dB, is 26.5–31.5 GHz. The measured beamforming angles from input port 1 to input Port 4 of the Butler matrix are +46, −16, +15, and −50°, respectively. The corresponding antenna gains from input Port 1 to input Port 4 are 11.57 dB, 14.284 dB, 10.94 dB, and 12.864 dB, respectively. The dimensions of the Butler matrix and the slot array antenna are 56.8 mm × 21.2 mm × 0.254 mm. The dimensions of the SIW transmission channels between the Butler matrix and input Ports 1– 4 are 16.9 mm × 34 mm × 0.254 mm.