RADIO PHYSICS AND RADIO ASTRONOMY

Subject and Purpose. Peculiarities of the TE₀₁ wave excitation in a circular waveguide located in the center of the flat mirror of a hemispherical open resonator (OR) are studied using the OR oscillation type TEМ_30q and the OR degenerate oscillation type TEM^*_11q  in the extremely high frequency (EHF) range.

Methods and Methodology. The efficiency of the circular-waveguide TE₀₁ wave excitation using the TEМ_30q and TEM^*_11q types of OR oscillations is evaluated through the factor of antenna surface utilization. Amplitude distributions of the OR oscillation fields were measured by the trial body method.

Results. It has been established that the efficiency, η, of the TE₀₁ wave excitation in the circular waveguide is not high when it is by use of the OR oscillation TEМ_30q. Things are different when the TE01 wave is excited with the inner ring of the TEM^*_11q degenerate oscillation field whereby the η value shoots up to 95.5%, the circular waveguide section radius being a = 0.993w₀, where w₀ is the radius of the field spot of the main oscillation type TEМ_00q on the OR flat mirror. The experimental studies have confirmed that the TE₀₁ wave excitation in the waveguide has high efficiency. The attachment of the circular oversized waveguide section worsens the OR loss by no more than 0.9 dB. The presence of the circular waveguide makes the TEМ₃₀₁₂ oscillation type transform into the TEM^*₁₁₁₂ degenerate oscillation.

Conclusions. The considered OR can be used as a storage resonator in the construction of electromagnetic pulse compressors in the EHF range, since the resonant system loss increases insignificantly, and the circular waveguide itself is oversized. It is easy to implement an interference switch in such a waveguide.

Keywords: open resonator, circular waveguide, excitation efficiency, trial body, oscillation quality factor

Manuscript submitted 27.04.2023

 Radio phys. radio astron. 2023, 28(3): 243-256

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