Method for calculating the properties of coupled-cavity slow-wave structures from their dimensions

In the development of computer models of coupled-cavity travelling wave tubes, it is necessary to have some means of calculating the properties of the slow-wave structure. Direct calculation is difficult because of the complexity of the shapes involved. One possible method makes use of the equivalent circuit representation of the slow-wave structure. In the paper it is shown that the parameters of the equivalent circuit can be calculated from the dimensions of the structure. Once these parameters are known, it is very quick and easy to compute the phase change per cavity and the interaction impedance at any frequency. The results obtained by this method are compared with those of experiment and it is shown that useful accuracy can be obtained.