Cut-Off Frequency Analysis of Ridged Rectangular Waveguide Based on Its Equivalent Circuit

This paper presents an analysis of cut-off frequency for a ridged rectangular waveguide based on its equivalent circuit. The conventional rectangular waveguide is employed as the initial configuration to determine the equivalent circuit which consists of capacitors and inductors. Values of both components are deriving by the cut-off frequency and source impedance. Here, a double-ridged rectangular waveguide is utilized to represent a ridged waveguide whereby its cut-off frequency is applied as a key parameter in the analysis. The proposed equivalent circuit was validated by comparing the cut-off frequency obtained from theoretical approach and EM & Circuit simulator software for several frequency bands. In addition, variation of space between ridges has also confirmed the validity of the proposed equivalent circuit. As a further investigation, the dielectric material loading into the conventional rectangular waveguide and the dielectric material insertion between the ridges are provided to demonstrate the performance of proposed equivalent circuit in lowering the cut-off frequency.