MICROWAVE CIRCUITS TECHNIQUE FOR MEASURING OPEN RESONATOR PARAMETERS UNDER CONDITIONS OF HYBRID MODE EXCITATION

摘要

The resonance frequency and unloaded quality-factor of a microwave resonator with one coupling element can be measured by the method of total impedance [1]. The methods of determination of losses in the coupling devices are developed [1,2], in particular, the determination of radiating losses in the coupling elements of open resonators (OR) [3,4], neglection of which results in regular errors. The method of total impedance, in its classical form, assumes the excitation of single modes in the resonator. The eigen frequencies of these modes are separated by the values exceeding several half-widths of the resonance curves. However, in the measurements of dielectric or magnetic properties of materials the "splitting" a resonant curve is observed [5] (removal of mode degeneration). Besides, in the range of a single mode resonance curve, widened owing to interaction of the resonator mode with analyzed sample, other modes can be observed [6]. Therefore, development of methods able to measure insertion losses and shift of resonant frequency of the working mode in the presence of the other closely located modes, is of significant interest. In [5], a resonator method of surface impedance measurement for "on pass" regime in the presence of the mode splitting has been offered. However, here it is required, that the quality-factors and the normalized frequencies for two components of a complex mode should be identical. We present here a method of measurement of the partial characteristics of two modes making a hybrid oscillation in the resonator with arbitrary Q-factors and coupling coefficients. The difference of modal eigen-frequencies and the coupling factor are calculated simultaneously.