Excitation of Waveguide Waves by Oscillations of Open Resonator

Using a functional that determines the surfaceutilization coefficient of aperture antennas, an analysis was performed of the efficiency of exciting the fundamental TE 10 and TE11 modes in rectangular and circular waveguides. Each waveguide is positioned at the center of the flat mirror of a hemispherical open resonator (OR). The waveguide modes are excited by the central field spots of the TEM_2.0.q (in Hermite-Gaussian functions) and TEM_1.0.q (in Laguerre-Gaussian functions) oscillations, respectively. It is shown that the maximum excitation efficiency of the TE₁₀ mode in a rectangular waveguide is 0.8901 when its transverse dimensions are a=0.9987_w0 and b=1.9799_w0 (w₀ - the spot radius of the fundamental TEM_0.0.q oscillation of the open resonator). In the case of a circular waveguide, the maximum excitation efficiency of the TE₁₁ mode is 0.8993 at a waveguide radius of a=0.6042_w0. Experimental studies were carried out in the four-millimeter wavelength range. The resonator is formed by a flat and a spherical mirror, each with a diameter of 60 mm. The spherical reflector has a radius of curvature of 85 mm. It was established that the presence of a circular waveguide with a diameter of 8.5 mm in the center of the flat mirror leads to only a slight increase in ohmic losses in the OR. Therefore, such a resonant system can be used for measuring the electrophysical parameters of solid dielectrics.