Reduction of SLL in a Square Horn Antenna in Presence of Metamaterial Surfaces by Using of Particle Swarm Optimization

Metamaterial surfaces with a low refractive index have been recently proposed in the design of the low side lobe level horn antennas based on engineering dispersion method. This paper explores a linearly polarized square horn antenna in the Ku-band for communication satellite reflector antennas. We study the designs of broadband metasurfaces and their use as coating layers on the interior E-plane walls of the horn. The design process includes combining the Particle Swarm Optimization technique with a full wave electromagnetic solver to model dispersion-engineered metasurfaces with surface impedance characteristics that support the desired hybrid modes. The obtained optimized metasurface is a low refractive index metamaterial with negligible losses that improves the conventional horn properties over the frequency band. The symmetric far field radiation patterns, the low side low levels and cross polarization levels and the aperture field distributions verify the hybrid mode operation of the horn. Moreover, this technique promises for a lighter horn with an easier manufacturer method compared with the conventional dielectric core loaded and corrugated horns.