Improvement of non-resonant perturbation measurement using S-matrix data

We report on the possibility of improving the phase measurements for the non-resonant perturbation techniques for estimating of the characteristic or interaction impedance in waveguides and slow wave structures. The measurement of the characteristic or interaction impedance is usually based on the nonresonant perturbation theory, which relates a normalized electromagnetic field strength with a small variations of the propagation constant between the perturbed and unperturbed circuit.