Design of a wide-gain-bandwidth metasurface antenna at terahertz frequency

This paper presents the design of a planar low-profile, wide-gain-bandwidth metasurface antenna at terahertz frequency. The proposed antenna consists of a metasurface and a planar feeding structure, both of which are patterned on an electrically thin, high-permittivity GaAs substrate. The metasurface, which is printed on the top of the substrate, consists of a periodic array of 5×5 square patches, while the planar feeding structure, which is printed on the bottom of the substrate, is a wideband, leaky-wave, open-ended slotline, which is fed at the center. The antenna with a single feeding structure showed a maximum broadside gain of 9.8 dBi, a radiation efficiency of 69%, and a 3-dB gain bandwidth of 16% (0.34–0.4 THz). The antenna gain performance was significantly improved by exciting the antenna with an array of slit feeding and without changing the antenna size. The antenna with a multiple (five) feeding structure showed a gain of 15.5 dBi, a 3-dB gain bandwidth of 17.3%, and a radiation efficiency of 73%. This antenna achieved a size reduction of 31 times in terms of device thickness in comparison with the design of the lens coupled antenna while achieving a comparable gain. In addition to its high gain and wide-gain-bandwidth characteristics, the proposed antenna design exhibits a low-profile mechanical robustness, easy integration into circuit boards, and excellent low-cost mass production suitability.