Dual-layer 4x4 Butler Matrix for 5G application through Via Optimization

• Published in: ISAP 2024 - International Symposium on Antennas and Propagation
• Main Author: Mohd Redzwan F.N.; Abd Rahman N.H.; Yamada Y.; Subahir S.; Idrus I.I.; Jizat N.M.; Miswadi N.
• Format: Conference paper
• Language: English
• Published: Institute of Electrical and Electronics Engineers Inc. 2024
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85218194143&doi=10.1109%2fISAP62502.2024.10846466&partnerID=40&md5=d23334bf6415076321c68516dc3735c9

In a 5G base station, a Butler Matrix (BM) feed circuit is requested to achieve multibeam patterns while maintaining a compact structure. However, the conventional design and size raise issues in installation and efficiency, especially at the lower 5G band, the 3.5GHz. To cater to many antenna elements, the BM size is increased, and the losses are severe, affecting the phase sensitivity. To address these issues, a stacked 4x4 BM with a dual-layer thin substrate is connected through non-uniform vias that act as a fine-tuning mechanism, where the desired phase difference is obtained by adjusting the circular slot diameter of the via. The BM features a low-profile structure with a 1.03 Ȝ [1.1 Ȝ GLPHQVLRQ, a significant reduction from the conventional 4x4 BM. The designed BM measured results show transmission amplitude of -7dB, and an acceptable range of output phase difference at the operating band. © 2024 IEEE.