Quasi-stationary calculation of cutoff length of dominant wave of double- and four-ridged waveguides with layered dielectric filling of their central sections

Approximate analytical expressions allowing carrying out quasi-stationary calculation of cutoff lengths of dominant waves of double- and four-ridged waveguides with layered dielectric filling of their central sections when interfaces are perpendicular to the force lines of electric field are derived with the help of the equivalent network method and using computer at the final stage of obtaining numerical results. Calculation results of normalized cutoff length of dominant mode of double-ridged waveguide obtained by using the method of equivalent networks and the finite element method for different values of geometrical sizes of layered dielectric filling of it central section are compared.