Low-Profile Dual-Polarized Isoflux Antennas for Space Applications

Design, realization, and measurements of an X-band antenna for data downlink (DDL) from low Earth orbit (LEO) satellites are presented. This antenna has an isoflux radiation pattern and operates in dual circular polarization with cross-polar discrimination (XPD) higher than 18 dB on the operational bandwidth. Two solutions are first proposed: one realized by a metasurface with circular strips printed on a dielectric slab and another realized by concentric metallic corrugations. Starting from a basic scattering mechanism of a self-complementary ring-type metasurface excited by a perfectly polarized source, both these antennas are designed by optimizing an equivalent anisotropic impedance surface excited by a short hat feed. The corrugated antenna is realized and measured, confirming that the performances are compliant with the requirements for nextgeneration DDL antennas.