A Planar Binary Structure for Realizing Frequency Controlled Beam-Steering at 0.2-Terahertz Band

A novel frequency-scanning grating-reflector antenna operating in 0.2-Terahertz (THz) band is studied in this letter. The diffraction enhancement mechanism based on the planar binary structure was first proposed to improve the diffraction efficiency and to suppress the specular beam. Compared to the grating-reflectors with multilayered structures that have been implemented in microwave band, the proposed planar binary structure employs a periodic binary grating array and a single-layer substrate, which brings much convenience of fabrication and being extended to the THz band. The antenna system consists of a planar grating-reflector, a thin lens, and a feed horn placed at the focal point of the lens. The frequency-controlled beam-steering concept and the diffraction enhancement mechanism were verified by the quasi-optical measurements in 0.2-THz band. The measured scanning range is 15.45° over the frequency band 180-220 GHz. The specular beams are remarkably inhibited with the diffraction efficiency as high as over 96%. The proposed beam-steering antenna has potential applications for THz imaging with high frame rate.