Design and Analysis of Patch Antenna With 244° 3-dB Axial Ratio Beamwidth

Abstract

A novel design approach for broadening 3-dB axial ratio beamwidth (ARBW) of circular polarization (CP) patch antenna is herein introduced. A patch structure consisting of three pairs of slots and four coupled strips is firstly proposed and examined. In such a compact size of $0.216\,\,\lambda _{0} \times 0.216\,\,\lambda _{0} \times 0.013\,\,\lambda _{0}$ ( $\lambda _{0}$ is the free-space wavelength at the 2.42 GHz). By carefully studying the evolution and related impact of the patch structure, the ARBW broadening mechanism is thoroughly revealed. The far-zone fields are further studied by the theory of equivalent magnetic currents (EMCs), and two polarized degenerate modes TM10 and TM01 are generated to excite CP radiation. To better understand the working mechanism of the proposed parasitic structures, an equivalent circuit consisting of three networks is given. Finally, to validate the performance, the proposed antenna is fabricated and measured, the simulated and measured results of impedance bandwidth for $\vert \text{S}_{11}\vert \le -10$ dB is from 2.36 GHz to 2.48 GHz, and the measured 3-dB ARBW is 244° at plane $\varphi $ = 0°. Both simulated and measured results show that the proposed antenna is very promising for high elevation angle wireless applications.

Keywords

• 3-dB axial ratio beamwidth (ARBW)
• circular polarization (CP)
• coupled strips
• compact size
• equivalent magnetic currents (EMCs)
• degenerate modes