New active and reconfigurable butler matrix for 5G application

This paper describes a new system for steering antenna beams using a 4x4 Butler matrix and Varactor diodes. The Butler matrix allows for four beams to be generated, each pointing in a specific direction depending on which input port is excited. The Varactor diodes are used to adjust the phase shift of the signals going through the matrix, which allows the beams to be steered to different angles. The fabricated prototype of the system and tested it at a frequency of 3.5 GHz. The system performed well, with a reflection and isolation coefficient better than -15 dB over the entire desired frequency band, and an amplitude imbalance lower than ±1.5 db. They were able to steer the radiating beam to different angles depending on the bias applied to the Varactor diodes, with the beam being oriented from ±6° to ±18° when port 1 or 4 are excited and from ±32° to ±43° for ports 2 and 3. Overall, this system could be useful in applications where it’s important to be able to steer antenna beams to different angles, such as in radar or communication systems.