| As the application of terahertz（THz）technology continues to expand,its unique advantages in radar,imaging,and communication are increasingly demonstrated.However,the development of THz technology is closely related to the research and development of key THz devices.As one of the core key functional devices,the phase shifter aims to meet the requirements of large angle,low loss,easy integration,and high precision.Based on the key indicators of the phase shifter,this thesis conducts research on multiple microstructure units with fin-line loading and microstructure units with waveguide-inserted double branch junctions in two frequency bands of 340GHz and220GHz,respectively,and obtains the final optimized results.The main research work and related achievements of this thesis are as follows:1、Introduction to theory of THz phase shifters.This includes the key parameters of phase shifters,basic types of phase shifters,and microstrip transmission line theory.The key parameters of phase shifters mainly include phase shift accuracy,operating frequency range,phase shift range,and insertion loss.Regarding the types of phase shifters,we mainly introduce the working principles of loaded phase shifters,reflection-type phase shifters,and switch-type phase shifters.Finally,the relevant theory of microstrip transmission lines is introduced.2、Conduct research on THz multi-bit phase shifters with fin-line loaded microstructures at center frequencies of 340GHz and 220GHz.Firstly,based on the basic theory of fin-lines and the phase transition characteristics of vanadium dioxide（VO2）,a fin-line loaded dual branch multi-bit THz phase shifter is studied.The optimized results show that a 45°dual branch unit composed of a square split-ring resonator and a VO2metal patch meets the requirements of a multi-bit phase shifter,achieving a maximum phase shift of 185°in the frequency range of 330GHz to 350GHz with an insertion loss of less than 2d B.At the same time,within a bandwidth of 10 GHz,the maximum phase shift error is about 5.3°.Then,based on the previous research experience,a multi-bit terahertz phase shifter structure with fin wire loading single branch is proposed.Each probe-type single branch microstructure unit can meet the requirements of a terahertz phase shifter with a step of 22.5°and a four-bit dynamic adjustment.The multi-bit terahertz phase shifter can be implemented in the 215GHz～225GHz frequency band,and the maximum phase shift can be achieved at the 220GHz center frequency point of 174.9°,and the insertion loss is less than 1.4d B.3、A waveguide-inserted dual-branch THz multi-phase shifter structure is proposed in this paragraph.Optimization results indicate that the designed 22.5°,45°,and90°dual-branch phase shifting units meet the requirements of a multi-phase shifter.By combining different dual-branch units,a high-angle multi-bit THz phase shifter with a total phase shift of 336°and a step size of 22.5°within the frequency range of 215GHz to 225GHz can be achieved.The insertion loss within the frequency range of 215GHz to225GHz is within 2d B,and the phase shift linearity is good.In addition,the study investigated finlines and microstructure units,providing ideas for loading microstructure units and combining different microstructure units to achieve a multi-bit high-angle THz phase shifter.This research promotes the development of multi-bit high-angle THz phase shifter technology. |
