I. K. Kuzmichev

An open resonator for measurements of the strongly absorbing substances

Bubnov-Galerkin method is applied for simulation of electromagnetic processes in open resonator exited by open circular waveguide located in the center of plane reflector; the second reflector has the spherical shape. The obtained results are promising for application of proposed resonant cell for the study of electromagnetic properties of materials with high losses.

A resonance system for measuring complex permittivity of materials

Preliminarily it has been shown [1] that an open resonator (OR) attached to a certain-length superdimensional circular waveguide only maintains axially-symmetric TE01q oscillations (see Fig. 1, b and c). In addition, the resonant system of the kind features a single-frequency response over a wide frequency range and, hence, can be adopted for the determination of electro-physical parameters of materials. An approximate mathematical model of the resonator of the kind has been suggested, and its basic electrodynamical properties were theoretically studied and experimentally checked [2-4].

Segments of oversized waveguides in open resonant systems

The article discusses a hemispherical open resonator (OR) with a segment of circular or coaxial waveguide in the center of the plane mirror. Excitation efficiency for axially symmetric TE₀₁ and TM₀₁ modes in a circular and TEM and TE₀₁ in coaxial waveguides with help of TEM_01q, TE_01q and TM_01q OR modes is analyzed. It shows that the efficiency of excitation of these waves can be reached 90% in case of the appropriate choice of geometric dimensions of resonator.

An open resonant system for permittivity measurements in the millimeter wave range

A hemispherical open resonator (OR) with a segment of an oversized circular plunger waveguide in the middle of the flat mirror was presented in [1]. The open electrodynamical system of the kind produces axially symmetric oscillations. Experimentally it has been shown that the discussed OR features a single oscillation over a wavelength-order tuning range. In the present work, we will discuss the scope for permittivity measurements of cylindrical-shape samples by means of the given OR. For this purpose, cylindrical-shape TE01q-mode cavities are normally used in the centimeter wave region. But with reduction in the wavelength, the geometric size of the cylindrical cavity should be decreased in order to keep its single mode operation. So, the millimeter and, further, submillimeter wave cylindrical cavities become so small in geometric size that it is not practical to use them. At those wavelengths, the OR we suggest lends itself well because the diameter of the circular waveguide, an element of the OR design, measures several wavelengths. In addition, the absolute permittivity measurements are most favorable because they need not a preliminary calibration of the OR resonance frequency related to the permittivity of samples with known characteristics.