Effect Of The Structure And Physi-cal Parameters On The Frequency Response Characteristics Of The Periodic Structural Units

This dissertation focuses on the basic research on the electromagnetic frequencyresponse characteristics of the periodic structural units. Based on the two-andthree-dimensional periodic units, this dissertation investigated the frequency responsecharacteristics from the structure of periodic units and material’s electromagneticparameters.Firstly, based on the equivalent circuit theory and the equivalent electromagneticparameters theory, the frequency response characteristics of the periodic structure unitwere researched. By analyzing the frequency selective surface equivalent circuittheory, this dissertation presented the factors that affect the frequency responsecharacteristics, such as the shape, size, dielectric layer of periodic units, the incidentangle, the polarization mode of electromagnetic waves. It also presented that theincident angle of electromagnetic waves affect the grating lobe phenomenon offrequency response. In terms of the equivalent electromagnetic parameters theory, adetailed derivation was carried out to calculate the equivalent electromagneticparameters, and therefore, the transmission rule of electromagnetic waves inthree-dimensional periodic structure was presented and the effects of structure andelectromagnetic parameters on frequency response were analyzed.Based on the equivalent circuit and the equivalent electromagnetic parameterstheory, a ring-type structure model was set up by using Ansoft HFSS and CSTsimulation software, the two frequency response characteristic curves were obtainedbased on the finite element and finite integration time domain method. Thecorrectness of the numerical calculation was verified by comparing the difference ofthese two curves. Basing on this, the frequency response characteristics of the ringchip structure, the shape of Jerusalem and square gap structure unit are analyzed, theeffect of the factors such as cell shape presented by the equivalent circuit theory onthe frequency response characteristics of periodic structures units was confirmed.Furthermore, calculation results of three-dimensional models with upright cylindricaland hollowed cube periodic structures confirmed that it is reasonable to analyzethree-dimensional periodic structures by equivalent electromagnetic parameterstheory.Based on the results of the numerical simulation, samples of frequency selectivesurface units which were adopted in numerical simulation were made by using themethods of screen printing and laser etching, respectively. The frequency responsecharacteristics of the samples with different sizes and shapes were obtained bytransmission method based on Agilent E8257D signal generator and Agilent E7405A spectrum analyzer. By comparing the results by numerical simulation andmeasurement, the validity of the effect of structural parameters on the frequencyresponse characteristics was verified, furthermore, a conclusion that the frequencyselective surface units by laser etching method had much higher precision of resonantfrequencies than that by screen printing method was given.