Axial ratio analysis of single-feed circularly polarized resonant antennas

An unusual axial ratio analysis based on a quantitative study of the relative magnitude of the far-field radiated by each one of the two orthogonal quasi-degenerate modes excited in a single-feed circularly polarized resonant antenna is presented. Such analysis can be applied to those single-feed circularly polarized resonant antennas whose radiating element layout exhibits at least one symmetry plane. The proposed quantitative analysis gives to the antenna designer more information and physical insights than a conventional parametric analysis of the axial ratio behaviour versus frequency. As an example, the proposed approach is applied to a number of circularly polarized antennas presented in the open literature. © 2014 Taylor & Francis.