Abstract:To address the issues of complex structure and high fabrication difficulty associated with compact multi-beam antennas in the terahertz frequency band, a terahertz Luneburg lens antenna and a partial Maxwell Fisheye(PMFE) lens antenna operating in the 355 GHz band are proposed. Both antennas use a periodic metallic bed-of-nails structure to realize a gradient refractive index surface wave lens with a minimum structural dimension of 60 μm. To regulate the beam direction in the non-scanning plane, corrugated rings are loaded on the edges of the surface wave lenses. In addition, the waveguide feeding array and the surface wave lens are designed as one piece to ensure structural integrity. High-precision 3D printing(10 μm precision) combined with magnetron sputtering are employed to realize the metallization of two surface wave lenses and low-cost realization of terahertz antenna prototype. The simulated results show the beam scanning capability of ±60° and ±72° for the Luneburg lens antenna and PMFE lens from 350 GHz to 360 GHz, respectively. The Luneburg lens antenna is verified by prototype fabrication and testing, which demonstrates good impedance matching and multibeam scanning performance from 350 GHz to 360 GHz, with a beam scanning range of ±60°, a gain higher than 16 dBi, and a beam-scanning loss better than 1.2 dB. The agreement between the measured and simulated results demonstrates the feasibility of this scheme and provides a new design idea and technology choice for the realization of terahertz multibeam antenna design.