A broadband circularly-polarized antenna with wide axial-ratio beamwidth

Abstract

A broadband circularly polarized antenna with wide axial-ratio beamwidth utilizing a wideband power divider network is presented. The vertical and horizontal paired-dipoles are used as the antenna elements, which are excited by a 1-to-4 sequential broadband feeding network. Through a rational design of the spacing between two parallel dipoles and the feeding network, an antenna with broad impedance and axial-ratio bandwidth and wide 3-dB axial ratio beamwidth is achieved. A prototype of the proposed antenna is designed, fabricated, and tested. It can achieve a measured impedance bandwidth for VSWR≤1.5 of 67.9% and a 3-dB axial-ratio bandwidth of 42.5%. Moreover, the antenna has wide 3-dB axial ratio beamwidth of more than 120° ranging from 1.16 to 1.46 GHz. The proposed antenna is low profile, and can be built using low-cost printed circuit fabrication methods.