Butler Matrix Design and Simulation For 5G Applications

This paper adduces 4x4 butler matrix beamforming network employing a new technique in transmission line structure-- open circuit coupled lines and a metamaterial structure of composite right-left handedness formed by interdigital capacitors. The basic design elements for butler matrix per suites 45 degrees phase shifter, quadrature-coupler cascaded crossover (0dB) and 90 degrees hybrid coupler. Central operating frequency considered is 3. 5GHz and flame-retardant (FR-4) ($\varepsilon$ r=4.33 and h=1.66mm). The design and simulation are carried out in COMSOL Multiphysics V5.5 software. Insertion and isolation losses from simulation are $\geq$-10dB and return loss better than 16 dB. The BM aspects are 68. 8mm in width and 66. 9mm in length. The simulated phase difference are ±45° and °135° with tolerance of 70. This metamaterial-based beamforming network heralds for 5th generation (5G) wireless beam steering technology envisioned for deployment in India for phased array antenna systems.