| With the continuous progress and development of science and technology and the upgrading of communication system,the sixth generation of mobile communication technology is coming to us.The frequency utilization has entered the terahertz(THz)band,and THz communication has become a hot field of technology research in various countries.Since THz radio wave has the characteristics of both traditional microwave and light wave,it has many advantages in space science,passive remote sensing,security detection,biomedical and astronomical observation.This paper designed a kind of work in the terahertz band 220 GHz 2×2 waveguide slot antenna unit structure,and the unit structure to optimize,due to the antenna structure is composed of multilayer metal plates,so the structure of each layer in the process of optimization parameters are optimized,finally achieved a can gain 220 GHz at center frequency of 13.9 d Bi.The element array element has a relatively consistent pattern on plane H and plane E,the width of the main lobe is about 34.1°,and the side lobe level is less than-16 d B on both plane E and plane H,which can meet the design requirements.A terahertz waveguide slot antenna array operating at 220 GHz frequency is designed on the basis of the element array.The number of antenna elements is 16×16.The gain of the antenna reaches 32.7d Bi,which is relatively high.The sidelobe level is-13.4d B,which can meet the design requirements.The simulation results show that the impedance bandwidth of the waveguide slot antenna array is about 4.5%(215GHz-225GHz),which is consistent with the bandwidth of the cell array.The simulation efficiency of the antenna can reach 98%.In order to enhance the degree of freedom of the feed structure and extend the bandwidth,a double-layer parallel feed structure is designed,which consists of an E bend,four T junctions and an H junction from the feed aperture to the coupling aperture.Each basic E bend has a notch at the bevel to reduce the reflection.Each part of the feed network is simulated and optimized respectively,and the feasibility of the feed network is shown in the joint simulation with the array.A stepped feed structure is adopted to connect the BJ2200 standard waveguide interface with the feed network and realize the feed.In the process of unit design,because the bandwidth of the unit used for processing is not high enough,a design to solve the low bandwidth is given,so that the bandwidth of the unit can meet 9%.As the thickness of the thinnest metal plate in this structure is0.1mm,it is difficult to avoid errors caused by pressure in the processing,which will affect the performance of the antenna.Therefore,this paper still chooses an antenna array with a bandwidth of 4.5% for processing,and makes preparation for error analysis for processing the real antenna.The possible errors in each part of the antenna feed network and in each direction of the whole array antenna are simulated and analyzed.Otherwise,two other types of waveguide slot array antenna are designed:multilayer slot gradient antenna and circularly polarized slot array antenna.The multilayer slot gradient antenna can achieve a high gain of 32 d Bi and a low sidelobe level of-13.4d B at the central operating frequency of 220 GHz.The axis ratio of the circularly polarized waveguide slot array antenna at 220 GHz can be less than 3d B to achieve the effect of circular polarization. |
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