Wide-scanning Circularly Polarized Reflector-based Modulated Metasurface Antenna Enabled by a Broadband Polarizer

TL;DR

This paper presents a wide-scanning circularly polarized leaky-wave antenna using a broadband polarizer and anisotropic metasurface, achieving high gain and polarization purity over a broad frequency range without complex feed networks.

Contribution

It introduces a novel antenna design combining a modulated metasurface with a broadband polarization converter, enabling frequency scanning and high polarization purity with simplified feeding.

Findings

Gain exceeds 18 dBi from 16 to 21 GHz

Axial ratio remains below 3 dB across the bandwidth

Prototype measurements confirm simulation accuracy

Abstract

A circularly polarized leaky-wave antenna capable of frequency scanning is proposed in this paper. The main objective is to achieve high gain and polarization purity without the need for a complex feed network. The antenna consists of two independent modules: (1) Anisotropic modulated metasurface antenna (MoMetA) for generating vertically polarized radiation with an operational scanning range of 19 to 47 degrees in elevation; (2) Wide-band polarization converter with high angular stability and capable of converting vertically linear polarization into circular polarization (CP). Aperture field estimation (AFE) method is used to design the antenna with high accuracy in predicting far-field pattern without the need for full-wave simulations. The gain of antenna in the bandwidth of 16 to 21 GHz is obtained better than 18 dBi. Simulation results show that the axial ratio in the maximum gain direction is lower than 3 dB all over its operational frequency bandwidth, demonstrating the proper operation of polarizer. In order to verify the simulation results, one prototype of the antenna is fabricated and its radiation patterns are measured in an anechoic chamber