Side lobe level reduction and gain enhancement of a pyramidal horn antenna in the presence of metasurfaces

Abstract

In this study, the design method and experimental presentation of low-refractive-index metasurfaces have been reported. These metasurfaces are employed in the interior E-plane walls of a pyramidal horn antenna. The target is a linearly polarised horn antenna with low side lobe levels (SLLs) and symmetric radiation patterns in the Ku band (13–18 GHz) for satellite communications. Particle swarm optimisation algorithm has been applied to the design procedure to achieve low-loss dispersion-engineered metasurfaces with desirable surface impedance characteristics. The metasurfaces were fabricated using precise low-cost printed-circuit board technique. There was perfect agreement between the measurement and simulation results. The fabricated horn showed low SLLs and an increase in the gain across the entire bandwidth. The SLLs are reduced by 14–29 dB in the E-planes and the gain is improved by 1.2–2.3 dB compared with a corresponding conventional horn. The far field radiation patterns of the metahorn verify the metasurface design approach. Furthermore, this method assures a lighter horn with an easier manufacturing technique in comparison with the other conventional horns, such as corrugated horns.