Short-Length and High-Aperture-Efficiency Horn Antenna Using Low-Loss Bulk Anisotropic Metamaterial

Abstract

An empty horn antenna is filled with a bulk anisotropic metamaterial to enhance its gain and aperture efficiency. Radiation patterns in both the E-plane and the H-plane are improved owing to the anisotropic permittivity and the anisotropic permeability. Aperture efficiency over 70% is achieved despite of its short longitudinal length <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\sim {\lambda _0}$</tex> </formula> . Insertion loss below 0.18 dB and energy reflection below <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$ - 20~\hbox{dB}$</tex> </formula> are obtained, which are quite small compared to most metamaterial-based antennas. The metamaterial-filled horn is fabricated and tested, and the measured results agree very well with the simulated results.