Quasi-static calculation of cutoff wavelengths of dominant modes of rectangular waveguides with one septum and two septa with central symmetrical placement of dielectric slabs in their capacitance gaps

Analytical expressions for calculation the dominant mode cutoff wavelengths of rectangular waveguides with one and two T-septa with central symmetrical placement of dielectric slabs in their capacitance gaps are obtained in quasi-static approximation on a basis of equivalent network method. Results of calculation of normalized cutoff wavelength of the lowest mode of rectangular waveguide with T-septum with the central symmetrical placement of dielectric slab in its capacitance gap obtained by using the method of equivalent networks and the finite element method are compared.