Compact Multibeam Array with Miniaturized Butler Matrix for 5G Applications

This paper presents the design and implementation of a miniaturized beam steering network that produces broadside beams when it is fed with a compact antenna array. Butler Matrix (BM) was used as the beam steering network. It was completely built from a miniaturized 3 dB hybrid-couplers in planar microstrip technology. It was configured by feeding the BM with a Planar Inverted-E Antenna (PIEA) array separated at 0.3 lambda as against the 0.5 lambda separation. This makes the BM produce a major radiation pattern at the broadside. Apart from the miniaturization, no modification was made from the BM side. However, employing effective mutual coupling reduction techniques helped to design the compact PIEA array. The validity of this BM based multibeam PIEA array was demonstrated by comparing the simulation results of the reflection coefficients, transmissions coefficients and the radiation pattern with measurements. The measurement results showed good agreement with simulations.