Compact High-Performance Lens Antenna Based on Impedance-Matching Gradient-Index Metamaterials

A planar wavefront transformation lens based on gradient-index metamaterials is proposed. The designed lens is composed of isotropic and inhomogeneous metamaterials and can reach impedance matching with free space. Based on the impedance-matching metamaterial lens, we present a compact high-gain and high-aperture-efficiency horn-based lens antenna working from 8 to 12 GHz. At the center working frequency of 10 GHz, the performance of the antenna is significantly improved and the measured gain increases to 17.7 dBi, which is 6.5 dBi higher than that of the original H-plane horn antenna. The half-power beamwidth and sidelobe level in the H-plane reduces to 6.2° and 15.3 dB, respectively, and the aperture efficiency reaches 94%. Such performance is much better than that of the conventional optimal H-plane horn antenna.