Circular Polarization of Periodic Leaky-Wave Antennas with Axial Asymmetry: Theoretical Proof and Experimental Demonstration

TL;DR

This paper proves that axially asymmetric periodic leaky-wave antennas inherently produce elliptical polarization due to in-phase quadrature radiation components, and demonstrates how axial asymmetry can control and minimize the axial ratio experimentally.

Contribution

It provides a theoretical proof of the elliptical polarization in axially asymmetric LWAs and experimentally demonstrates the control of axial ratio through asymmetry.

Findings

Radiation components are in phase quadrature, causing elliptical polarization.

Axial asymmetry controls and minimizes the axial ratio.

Experimental validation with CRLH and SFP LWAs.

Abstract

The paper includes two contributions. First, it proves that the series and shunt radiation components, corresponding to longitudinal and transversal electric fields, respectively, are always in phase quadrature in axially asymmetric periodic leaky-wave antennas (LWAs), so that these antennas are inherently elliptically polarized. This fact is theoretically proven and experimentally illustrated by two case-study examples, a composite right/left-handed (CRLH) LWA and a series-fed patch (SFP) LWA. Second, it shows (for the case of the SFP LWA) that the axial ratio is controlled and minimized by the degree of axial asymmetry.