Beam-Switching antenna array with dual-circular-polarized operation for WiMAX applications

Abstract

In this paper, a multi-layered dual circularly-polarized (CP) beam-switching antenna array is presented. The designed beam-tilting antenna array includes dual CP elements to support polarization diversity and pattern switching and two symmetrical novel combinations of the Butler matrix in two sides of radiating elements. The Butler matrix input ports on each side of the 1 × 4 arrangement of antenna elements control the polarization diversity. The Butler matrix consists of the broadband phase shifters and patch couplers. The proposed phase shifter is designed based on the aperture coupling technique for extending its 45-degree phase bandwidth. The single element of the antenna includes a reflector and two layers of substrate. The polarization of the proposed element is controlled with two microstrip lines at the end of a 90-degree patch coupler and a circular slot plays as the radiation section at another side of microstrip lines. The parasitic patch, helps to improve the impedance bandwidth and gain of the element. The proposed beam-switching antenna array supported WiMAX applications. The beam-forming network is fabricated and measured. The measured results of the fabricated antenna have a good agreement with simulated ones.