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Analysis Of Single - Mode Bandwidth Of Waveguide High - Order Mode And Ridge Waveguide By Deformation Difference Method

Posted on:2014-10-08Degree:MasterType:Thesis
Country:ChinaCandidate:L J YouFull Text:PDF
GTID:2208330452453984Subject:Radio Physics
Abstract/Summary:PDF Full Text Request
The bandwidth of a new waveguide inevitably involves waveguide’s high-ordermode, analysis of the waveguide’s discontinuity and research on multiple mode’semission and propagation. Successive over-relaxation of finite differencemethod(FDM) of solving the waveguide’s dominant mode is an effective method, butthe convergence condition requires that the matrix must be positive semi-definite.When the FDM is directly used to calculate the cutoff frequency of the high-ordermodes of waveguide, this condition is not satisfied. In this paper, the numericalmatrix directly obtained by the FDM is refined to make it positive semi-definite forall modes, then the cutoff frequencies of the high-order modes can be obtained by thesame procedure with calculating one of the dominant modes. The cutoff frequenciesof the high-order modes rectangular waveguide, L-shape waveguide, and symmetricridge waveguide have been calculated by the modified FDM. The bandwidth of thedominant mode’s of several kinds of the ridge waveguide have been given by themodified FDM.Firstly,the basic principle of the FDM is briefly introduced. The meshsubdivision method and differential formula of the FDM in the rectangular coordinatesystem are also discussed.Secondly, the coefficient matrix of the five-point difference formula istransformed into the positive definite matrix for all high-order modes of thewaveguide by the matrix transformation, the accuracy and effectiveness of themodified FDM have been demonstrated by analysis of engineering examples.Finally, the dominant mode bandwidth of three complicated cross section ridgewaveguides have been given, and the changing law between main mode’s bandwidthand the waveguide’s design parameters has been obtained. For single ridgedwaveguide, double-ridge waveguide and antipodal ridge waveguide, when theirridges are located in wide and narrow side, its influence has been analyzed fordominant mode’s bandwidth, and the result has be shown that the bandwidth of narrow ridge waveguide is less than that of the long ridge waveguide.
Keywords/Search Tags:modified FDM, high-order mode, cutoff frequency, ridge waveguide, dominant mode bandwidth
PDF Full Text Request
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