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This article presents a fully metallic waveguide- based multibeam antenna operating at the band from 410 to 480 GHz. The multibeam function is achieved based on the sliding aperture technique. The antenna is composed of a beamforming network based on self-compensating waveguide phase shifters, a parallel plate waveguide (PPW), and seven waveguide feeders. Each self-compensating phase shifter is realized by equal-length widened-and-grooved waveguide sections with a low-dispersion phase delay, which ensures a wide operating band. The design method of the beamforming network and the phase shifter is detailed. A prototype is manufactured using high-precision computer numerical control (CNC) machining and experimentally verified on S-parameters and radiation performances. The measured results show good impedance matching at all ports and low mutual couplings between them. The achieved beam scanning ranges within the band from 410 to 480 GHz are wider than ±30° with scan losses lower than 2.5 dB. The excellent agreement between the measured and simulated results verifies the design approach and the manufacturing technique. This work demonstrates a practical solution to sub-terahertz (THz) passive multibeam antenna with a robust and reliable metallic structure.

This letter presents a multibeam wide-angle scanning antenna based on the E-plane-focused partial Maxwell fish-eye (PMFE) lens operating in Ka-band. The gradient equivalent refractive index distribution of the lens is realized by the parallel-plate waveguide partially filled with dielectric material, which can support the E-plane focus. The lens is fed by a series of rectangular waveguides arranged along the straight cut line to realize the multiple beams. To improve the impedance matching, the dielectric wedges are loaded in the interface between the feeders and the lens. The E-plane broadening of waveguide feeding ports effectively alleviates the gain drop of wide-angle scanning. The measured results of the prototype show a beam scanning range more than ±90° with the aperture efficiencies between 57% and 85.7%. The good impedance matching is also obtained in the operating band. The proposed PMFE lens antenna has the application potential in the low-cost millimeter wave multibeam systems.

This letter presents an experimental realization of a subterahertz metallic gradient index (GRIN) lens multibeam antenna operating at 355 GHz. The antenna is composed of a surface-wave Luneburg lens based on a bed of nails and a feeder array of nine WR-2.2 waveguides. The lens and the feeding structures are fabricated by the same high-precision 3D printing technique and are metalized using magnetron-sputtering gold coating. The antenna has been measured, showing good reflection coefficients below −12.5 dB at all ports and multiple independent beams covering a range of ±60°, which agree very well with the simulation. The measured gains are above 16 dBi and the scan loss is below 1.2 dB. This work demonstrates a novel manufacture and implementation approach for metallic multibeam lens antennas at subterahertz frequencies.