Circularly Polarized Beam-Steering Antenna Array With Butler Matrix Network

A circularly polarized switched-beam patch antenna array with butler matrix is designed and experimentally demonstrated in this letter. With suitable rotation technique, circular polarized radiation can be improved for beam steering. Also, this technique enhances the axial-ratio (AR) bandwidth within its scanning angle. Measured results showed this array has an impedance and AR bandwidth over a frequency range of 5.75-6.2 GHz when the main beam of array is scanned to different directions. Good agreement is observed between simulation and measurement.