A Technology Research On Frequency Selective Surface And Folded Waveguide In Terahertz Band

Frequency Selective Surfaces(FSSs)and Folded Waveguides are two of the essential devices for the selection to and transmission of electromagnetic waves.FSS is a spatial filter constructed by the periodic two-dimensional extension of basic units,by the parameters of whose fabric electromagnetic waves of a certain frequency band manage to be selected;while folded waveguide is known as a new type of electronic injection structure for its wide application in aerospace,military etc.The development of terahertz technology has kept expanding the available frequency band for electromagnetic wave devices.Meanwhile,the processing technology is being stressed more by the need for miniaturization of the devices.In order to meet the requirement of low insertion loss near 183 GHz and that of high isolation near 118 GHz,influences of the parameters concerned on FSS's performance have been studied by simulations,and a comprehensive solution has been offered by the optimization of FSS's structure.A complete processing flow of fabrication has been designed,through which high-precision single-layer FSSs are able to be prepared by MEMS technology.Moreover,high-precision alignment of multi-layer FSS gets accomplished by the proposal of a methodology based on lithography positioning and laser drilling.The insertion loss has been examined by terahertz test system,showing a good agreement of simulated curves with the experimental ones.The requirements for insertion loss and isolation can be seen met in principle respectively,when the number of layers is properly set.On the other hand,preliminary design of the folded waveguide is conducted encompassing the dispersion characteristics and coupling impedance.A processing flow of twice-photolithography and twiceelectroforming based on mandrel electroforming has been put forward to maintain the accuracy of fabrication.In order to ensure the positional accuracy and collimation of the ultra-fine electronic injection channel(20 ?m),the polymer wire fixing mechanism was innovatively designed.