Dominant Mode And Higher Mode K_c Cad Calculation. Ridge Waveguide

Ridge waveguide is a kind of guide wave sturcture that often used, which can be formed from rectangular waveguide. Compare to the normal rectangular waveguide, ridge waveguide has the character of broader bandwidth, smaller dimension, lower equivalent characteristic impedance, etc. Because of these merits, it is used more and more widely, such as broadband ridge waveguide filter, broadband direct coupler, diplexer, frequency converter, phase shifter, ridge waveguide slot antenna array, and so on.It is more difficult to analyze and design ridge waveguide components because the boundary condition of ridge waveguides is far more complex than rectangular ones. KC of each higher mode in ridge waveguide is a very important parameter, once KC is obtained, the wavelength,phase constantβ,phase velocity, waveguide wavelength, equivalent reactance, equivalent admittance and so on can be obtained simply.Then ridge waveguide devices can be designed based on these paremeters. In view of the widely use of ridge waveguides, the research of KC is very important in practice.As mentioned in above, the boundary condition of ridge waveguide is quite complex, so to solve the field equations directly is very tedious and complicate. Equivalent circuit method is usually used before.This method has apparent defect, that is,the ignorance of higher order mode effect, which can greatly affect the computational accuracy.In cases that require high accuracy, this method is unusable.The goal of this paper is to obtain a method that can compute the KC parameter of each higher mode rapidly and precisely, and then write corresponding programs.On the basis of foreign and domestic references, after carefully comparison, the transverse technique of the mode matching method is adopted in this paper. During the programming, Fortran Language is used, and the rooting isbased on the well-known Newton method. The results are compared with the data that published on foreign authoritative issues,very good agreement can be found【13】,【28】. A ridge waveguide filter is designed based on the results of this paper,the simulation curves agree with the mesured curves very well.