Two-dimensional scanning of circularly polarized beams via array-fed Fabry–Perot cavity antennas

In this paper, we present an original Fabry–Perot Cavity Antenna (FPCA) characterized by a Polarization Conversion Metasurface (PCM) used as the top Partially Reflecting Surface (PRS). The main feature of the PCM consists in being capable to convert a linearly polarized (LP) wave into a circularly polarized (CP) one. Being a 2-D leaky-wave antenna (LWA), the device is able to perform an elevation scan by just sweeping frequency between 27 and 28.5 GHz, thus obtaining an azimuthally omnidirectional pattern evolving from a broadside pencil-beam toward a conically shaped one, sweeping in the elevation plane from the broadside up to nearly 40°. By further considering a feeding system composed by multiple identical LP sources, selecting the inter-element phasing, we are able to achieve the radiation maximum on a custom azimuth plane, thus obtaining a fully electronical CP beam steering.