Highly-efficient tunable dipole-driven Yagi–Uda antenna with end-fire radiation for terahertz application

Abstract

This paper presents a highly efficient tunable dipole antenna with omnidirectional radiation. The main radiator of the hybrid dipole is designed using a perfect electric conductor, whereas tunability has been achieved using graphene strips in the antenna’s proximity. The dipole antenna resonates at 1.3785 THz and provides a bandwidth (BW) of 8.58% for the graphene’s chemical potential (μc) equal to 0.6 eV. The peak gain and total efficiency (ηTotal) are 1.46 dBi and 83.13%, respectively. The proposed dipole provides tunability from 1.32 to 1.411 THz by varying μc from 0.4 to 0.7 eV. Further, a compact dipole-driven tunable Yagi–Uda antenna has been designed with end-fire radiation. The proposed Yagi–Uda antenna has a size of only 90 μm × 60 μm, i.e., 0.61λg×0.38λg, where λg is the guided wavelength calculated at 1.3631 THz and provides tunability from 1.328 to 1.5 THz. The peak gain, front-to-back ratio (FBR) and ηTotal at 1.3631 THz for the μc = 0.6 eV are found to be 4.93 dBi, 17.3 dB, and 63.36%, respectively. A practical parallel plate DC biasing configuration with a common ground plane has also been proposed to independently tune the μc of each element in the passive Yagi–Uda array. The proposed Yagi antenna provides reasonable gain and FBR to cater for high propagation loss in the terahertz regime.