| The electromagnetic field as an uniform plane wave that propagates in the specific direction and is incident onto a parallel-plate transmission line of reduced height generates fringing electric fields and saves its electric energy in vicinity of the discontinuities. Thus, many approaches have been proposed to this discontinuity problem of a guide with several forms. The equation introduced in Waveguide Hand book(WGH)[19] is an example of results by numerical methods such as variation, integral equation[31], equivalent static, and transform method. In this thesis, a Hahn's function, that is a classic equation about the discontinuity susceptance, is applied to determine the cutoff wavelength and to depict the field distribution of Double-ridged Waveguide (DRW) and Quadruple-ridged Waveguide (QRW), and compared with simulation results using the equation of WGH and Ansoft HFSS.; The perturbation technique has been used to expect EM characteristic changes like cutoff wavelength and determine the real and imaginary part of the complex permittivity due to some changes in the unperturbed shape. Due to the possibility of wide bandwidth (BW) at the specific dimension condition, it is used to calculate the BW of Chamfered DRW(CDRW) and applied to QRW(CQRW).; From the result of works like appropriate equation formulations and numerical simulations, the validity of Hahn's function as a primary factor of discontinuity susceptances of ridged waveguides and that the noticeable BW improvement of DRW and QRW through only shape perturbations isn't possible are confirmed. |
