Low-profile Dual-polarized Isoflux Antennas for Space Applications

Design, realization and measurements of a 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 crosspolar discrimination (XPD) higher than 18dB on the operational bandwidth. Two solutions are first proposed: one realized by a metasurface with circular strips printed on a dielectric slab, and one 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 performance of the two designs are compared. The corrugated antenna is realized and measured, confirming that the performances are compliant with the requirements for next generation DDL antennas.