A. Ya. Kirichenko

Giant radiofrequency magnetoabsorption in La0.5Sr0.5CoO3 cobaltite

Giant radiofrequency magnetoabsorption in La0.5Sr0.5CoO3 polycrystalline lanthanum cobaltite is studied in the temperature interval 77–300 K and 0.5–12.5 MHz frequency range. The specimen’s Curie temperature TC is about 250 K. The magnetoabsorption is found to increase with decreasing frequency, reaching 58% at f = 0.5 MHz near the Curie temperature. The results are satisfactorily explained based on the known physical ideas of high-frequency wave absorption in magnetic materials. The effects of giant magnetoabsorption and rapid variation of the absorption near the Curie temperature can be used in radiofrequency sensors of the magnetic field and temperature.

A spherical microwave discharge induced at atmospheric pressure

A discharge induced at the end of an antenna in a flow of argon outgoing into the free space in a coaxial microwave plasmatron is described. Increased energy density supplied to the plasma leads to structuring of the microwave discharge. Effects of the antenna geometry, supplied power, and argon flow rate on the discharge structure are studied.

The effect of gap width between disks on the Q value of a laminar dielectric disk resonator

The influence of the gap width between disks on the Q value and resonance frequency shift of a laminar dielectric disk resonator operating on whispering-gallery modes has been studied. It is established that an increase in the air gap between disks leads to growth in resonance frequency f of the selected mode and can increase the Q value of the laminar dielectric disk resonator as compared to that of an analogous usual (monolithic) disk resonator.

Slot line excitation of whispering gallery oscillations in shielded dielectric resonators

Electrodynamic characteristics of a half-disc shielded dielectric resonator operating in the 8-mm wavelength range have been investigated experimentally. A slot line was proposed for the excitation of whispering gallery modes in such resonator. It has been found out that the proposed excitation technique is effective and allows the high-Q oscillations of higher orders to be excited in a shielded dielectric resonator without additional energy losses. The partial shielding of the resonator in question was proposed for its spectrum rarefaction.

Using of gunn diode based self-oscillator is stabilised by quasi-optical dielectric resonator for determination of dielectric parameters of liquids

While measuring complex permittivity of media by resonator methods is used measuring of resonator frequency and its Q-factor if it is filled with reference and measuring media [1]. If measuring complex permittivity of heavy absorbing media the resonator is filled partially of investigated media [2]. At that on changing of frequencies resonator is stabilized by resonator and filled with reference and measuring media the values of real and imaginary parts of permittivity are determined. For the imaginary part of permittivity measuring is used measuring of signal level is passed through the resonator is partially filled with investigated media or changing of resonator Q-factor which estimated as bandwidth.

Dielectrometer measuring cell for investigation of liquids with high losses and high dielectric constant designed in form of the two - layer semispherical Teflon resonator

During the last time open dielectric resonators (DR) excited on whispering-gallery type waves due to their high Q-factor on the higher modes are used to investigate the dielectric properties of not only solid substances but also of liquids. For these purposes in the first experiments DR (which was used as measuring cell) being immersed directly in tested liquid. The investigated liquid influenced on external caustic of DR that led to frequency sift and changes of resonator Q factor. New achievement in creation of the dielectrometer measuring cells have appeared after the creation of the resonant structures in which certain geometrical parts of resonators are used. At first, such DR were created with metal mirrors. The subsequent researches [1] have shown that oscillations exist also without a mirror, which itself leads to condensate of a spectrum and reduction of the quality of resonator.

Influence of the screw on own frequency semi-disk partially shielded quasioptical dielectric resonator and frequency of the generator stabilized by the Gunn diode

The possibility of the mechanical realignment of the frequency of a generator on a Gunn diode by a metallic or dielectric screw, carried in a partly shielded quasi-optical dielectric resonator, is considered. The model, allowing influence value in a resonator by the screw on its own frequencies and frequency of generations, in a resonator stabilized generator, is designed.

Hemispherical dielectric resonator with concentric hemispherical hollow for liquid dielectrics investigations

A new measuring cell is suggested in order to investigate dielectric properties of liquids with great losses.

Higher azimuthal electromagnetic oscillations of HE-and EH-types in disc dielectric resonator

Features of higher azimuthal electromagnetic oscillations of “whispering” mode of HE-and EH-types in dielectric resonator of millimeter waveband are researched. Comparison of resonance characteristics of HE-and EH-types oscillations in such resonator is carried out.

Rarefaction of the spectrum of H-type whispering-gallery modes in a hemispherical dielectric resonator

A dense spectrum of H-type resonance oscillations (whispering-gallery modes) is observed in a hemispherical dielectric resonator excited by a capacitive slit situated on the equatorial metal mirror surface. The spectrum can be significantly rarefied by exciting the WG modes in the resonator by means of distributed coupling to a dielectric waveguide arranged in a certain special position relative to the hemisphere base.