The Analysis of Comb-Line Structures by Electromagnetic Field Theory

The paper examines the propagation characteristics of TEM coupled-bar structures in waveguide or between ground planes. For meeting the boundary conditions, the structure is divided into three sub-regions, for each of which solutions of Maxwell´s equations are obtained. To find the frequencies of pass-bands and stop-bands, the dispersion equations of the structures are derived by matching the fields at the common boundaries of the sub-regions. Numerical solutions of the dispersion equations are obtained by truncating the infinite series, which converge rapidly, so that only the first three space harmonics (?1,0,1) need be included. Double comb-line structures can be investigated by the same method. Comparison of theoretical and experimental results shows that they are in good agreement.