Measurement of dispersion and interaction impedance characteristics of slow-wave structures by resonance methods

The measurement of dispersion and interaction impedance of slow-wave structures from cold tests using resonance methods is described. The theory behind the measurements is given, stressing the assumptions made. Some of the shortcomings of the simple perturbation theory of interaction impedance measurement are explained. This simple theory is then developed to take account of two complicating factors which are often tacitly ignored: transverse fields and space harmonics other than the fundamental. It is made apparent that where these complications exist a reliable estimate of the interaction impedance can be made only if an approximate theory of the structure is available. Experimental details are given, including common difficulties and, where possible, methods of surmounting them.