Development of a High Gain 325–500 GHz Antenna Using Quasi-Planar Reflectors

A high gain quasi-planar reflector antenna for 325-500 GHz applications is investigated in this paper. The antenna is composed of four parts: a feeding horn, quasi-planar reflectors, choke slots, and an E-plane flared horn. The quasi-planar reflectors are designed to expand the H-plane radiation aperture. The choke slots are used to suppress the reflected wave from the sidewall and reduce the impact on the radiation performance. Detailed design principle is presented, and a prototype having a center frequency of 400 GHz is designed for demonstrations. To verify the design, the fabricated prototype is measured using a terahertz vector network analyzer in a THz chamber. Measured results show that the fabricated prototype achieves a wide impedance bandwidth of 43.75% from 325 to 500 GHz with a reflection coefficient below -20 dB. The maximum gain is 32 dBi at 500 GHz and the gain is higher than 26.5 dBi over the whole operating band. The proposed antenna has a quasi-planar form which can be accurately fabricated by using the conventional low-cost metallic milling process. It has a compact size, a low fabrication cost, a high radiation gain, and a wide operating bandwidth.