Research Of Terahertz Angular Filter Based On Metamaterial

With the development of terahertz sources and detectors,terahertz technology has been further studied.At present,terahertz technology has been widely used in many fields such as wireless communication,non-destructive testing,and security inspection.The terahertz angular filter refers to a device that can select terahertz waves in a specific propagation direction and has important application value in improving the signal-to-noise ratio of the terahertz detector and enhancing privacy protection in terahertz communication.This thesis has carried out research on the angular filter based on metamaterials,which has important theoretical value and practical significance.Firstly,the thesis introduce the research background and progress of the terahertz angular filter and summarize the problems in the current angular filter research.Secondly,the thesis used the equivalent medium theory and equivalent impedance theory to study the electromagnetic properties of the metamaterial structure.Thirdly,the angular filter suitable for the traditional light-wave frequency band and zero refractive index material was studied,and the design method of the terahertz angle filter based on the metamaterial structure was proposed.Finally,according to the previous design method,three-angular filters at terahertz frequency based on the split ring structure were designed using CST MWS 2017 electromagnetic simulation software.And the changing trend between the main structural parameters of the metamaterial structure and the performance of the angular filter was discussed.Among them,the metal layer structure of the first terahertz angular filter was formed by connecting two open rings with the same inner and outer widths through a metal bridge.At 0.940 THz,its transmittance to terahertz waves at a normal incident angle reaches 0.944.The 3d B angular domain bandwidth was 25.0^?.The metal layer structure of the second terahertz angular filter was composed of two back-symmetrical open square grooves.At0.186 THz,its transmittance to the terahertz wave at a normal incident angle reaches 0.920.The 3d B angular domain bandwidth is 7.2°.The metal layer structure of the third terahertz angular filter was composed of a square ring with the same period and four open inner ring structures.At 0.160 THz,its transmittance to terahertz waves at a normal incident angle reaches 0.981.The 3d B angular domain bandwidth was 9.8^?.The thesis processed and tested two of the terahertz angular filters.The simulation results were compared with the experimental test results.At last,the possible reasons for the formation of errors were analyzed.The terahertz angular filters designed in this thesis have good angle filtering performance,and they have important potential applications in privacy protection,high signal-to-noise ratio detectors,and suppression of antenna radiation side lobes.