High-Gain Dual-Band Transmitarray

We propose a novel linearly polarized, dual-band, and high-gain transmitarray based on multilayer frequency-selective surface structures. This is the first time for actualizing a dual-band transmitarray with more than 50% aperture efficiency. The unit cell is composed of four metallic layers without dielectric substrates between every two layers, which results in good match, low insertion loss, and high radiation efficiency. We introduce two kinds of rectangular slots in the design to control the magnitude and phase range of transmission coefficients in the two designed frequency bands through changing the slot length. The isolation between two bands is excellent and the interference can be ignored. The induced electric fields of the cell are also investigated in order to elucidate the working principle intuitionally. The proposed dual-band transmitarray with a square aperture (240x240 mm(2)) is designed, fabricated, and measured. A linearly polarized corrugated horn antenna is adopted to improve the aperture efficiency and ensure the similarity of the radiation patterns on E-plane and H-plane. Full-wave simulation and experimental results have very good agreements. It is demonstrated that the dual-band transmitarray works in two frequency bands 11.8-12.2 and 17.5-18.1 GHz simultaneously, and the peak gains in the designed central frequencies 12 and 18 GHz are 27.8 and 31.4 dB, respectively, which correspond to the aperture efficiencies (global efficiencies) of 52% and 53%. The proposed design has advantages of simple structure, small weight, low cost, and high performance, making it possible for real applications.