Reconfigurable Quad-Polarization Switched Beamforming Antenna With Crossed Inverted-V Array and Dual-Butler Matrix

This article presents a switched beamforming antenna array with reconfigurable quad-polarization and switched feed network. The proposed beamforming architecture is configured by a crossed inverted-V antenna array and a dual Butler matrix-based feed network to drive polarization diversity as well as beam steering. The crossed inverted-V array adopts a planar director to enhance antenna gain, while the outputs of the dual Butler matrix network are connected to each pair of the gain-enhanced inverted-V antenna elements. Furthermore, the dual Butler matrix is integrated with a polarization mode selection switch matrix. Based on the switching operations with the dual Butler matrix, both the beamforming and switchable polarizations among vertical, horizontal, right-hand circular, and left-hand circular polarizations (CPs) can be achieved. To verify the switched beam and quad-polarization performance, the proposed architecture with a
$1\times $
4 array configuration was implemented at 5.8 GHz. The measured 1
$\times $
4 antenna gain excluding the dual Butler matrix showed the average gain of 12.8 dBi(c) for all polarizations. Furthermore, the switched main beams driven by the dual Butler network and the polarization mode selection matrix showed four different angles in a
$1\times $
4 array.