Wide-Scanning Circularly Polarized Reflector-Based Modulated Metasurface Antenna Enabled by a Broadband Polarizer

A circularly polarized leaky-wave antenna capable of frequency scanning is proposed in this article. 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°-47° in elevation and 2) wideband polarization converter with high angular stability and capable of converting vertically linear polarization into circular polarization (CP). The aperture field estimation (AFE) method is used to design the MoMetA with high accuracy in predicting far-field pattern without the need for full-wave simulations. The gain of antenna in the bandwidth of 16-21 GHz is obtained well than 18 dBic. 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.