Abstract: In order to find a new kind of symmetrical double ridged waveguide which has optimal transmission characters, the paper puts forward two kinds of novel double ridged waveguides which have triangle and anti-trapezoid ridges respectively. The TE mode’s cut-off wavelength and single-mode bandwidth of two kinds of novel double ridged waveguides are calculated by the finite element method. It is shown that the ridged waveguide would gain a higher single-mode bandwidth as the distance of ridges is closer by analyzing transmission character changes along with the change curve of the ridged waveguides’dimensions, and that the maximal single-mode bandwidth is 8.0173.The anti-trapezoid ridge waveguide’s cut-off wavelength is longer than rectangle, trapezoid and triangle ridged waveguides which have the same dimensions, and the maximal value is 9.5. These results could provide instructions for miniaturization of ridged waveguide apparatuses. Finally plotted field patterns of the dominant mode and the first higher order show that the field intensity change is most enormous at the triangle ridge waveguide’s peak, and that the energy loss is greater.

Key words: ridge waveguide, FEM(finite element method), single-mode bandwidth, field pattern