Investigation Of Terahertz Multi-beam Antenna Based On Lens Beamforming Network

There is ever-growing demand of modern wireless communication technology for spectrum resources.As a result,the terahertz(THz)frequency band(0.1?10 THz)has been widely concerned and studied by researchers for its abundant spectrum resources.As the front-end of the wireless system,terahertz antennas have important research value.Among them,multi-beam antennas achieve high gain and wide coverage at the same time with a simple structure,while taking into account the cost and performance.Therefore,they have a broad application prospect.This paper focuses on the investigation of terahertz multi-beam antennas by focusing on the beamforming network and reflector surface.The main contents of this paper include the following aspects:First of all,the working principle and analysis method of Rotman lens are introduced.As a reference,a D-band three-port Rotman lens multi-beam antenna is designed based on the copper-based micro-coaxial process.The miniaturization of the lens is realized by using the single-ridge waveguide,the rectangular coaxial line and various transition structures.The antenna reaches a realized gain of 10.6 d Bi,and the three beams point to 0° and ±17.8° respectively,while the beam width is 19.2°,which meets the –3 d B beam overlap.Further,based on the bulk silicon MEMS process,a waveguide-type two-dimensional beam-scanning Rotman lens antenna that works at325?400 GHz is designed and processed.The lens contains seven input ports,ten output ports.The beam steers in H plane by loading leaky wave antennas.The antenna's realized gain is 26.7 d Bi.The multi-beam scanning range is –27.8°?27.8° at the center frequency,while the scanning beam covers a range of –30.7°?–17.3° as the frequency changes.The measurment results and the simulation results match well.Then,a multi-beam reflector antenna operating at 220 GHz is studied.Inspired by the offset-focus characteristics of the feed,an approach is proposed to improve the beam scanning performance of the array feed reflector antenna(AFRA)through the amplitude and phase control.In order to further broaden the beam coverage,reduce the scanning loss,and limit the amplitude dynamic range of the feed,optimization is taken about the space position and the array form.On this basis,three 1×4 linear arrays,witch work independently,are used to feed the offset paraboloid surface.The antenna achieves a beam coverage of –5.5°?6.5°,with the beam width of about 1°.The simulation realized gain is 39.9 dBi,and the scanning loss is 2.6 dB.