Monofrequency excitation of open resonator with inclined comb grating

The theoretical and experimental analysis of the open resonator with the reflection diffraction comb grating has been presented. This resonator has excitation where is close to the monofrequency mode. This results may be used for the elaboration of mm-wave quasi-optical devices such as generators, mixer, converter, wavemeters and others.     

Research on orotron oscillator with dispersive open resonant system

Theoretical and experimental results of an investigation into a new resonant system have been obtained. This system is named the sphere-corner-echelette open resonator (SCEOR) due to the employment of a mirror that was formed by two echelettes at the angles of 45° to the resonator axis. It turns ont that this resonator is excited on the specific modes not unique to others oscillating systems. There are presented the results of the experimental research of the orotron oscillator with the SCEOR. The spectrum of this device contains only the fundamental modes such as theT E M ₀₀₆,T E M ₀₀₇,T E M ₀₀₈. The efficiency of the orotron is improved, when all other factors are the same the orotron with a much used sphere-cylindrical open resonator.     

Input Millimeter-Wave Module with Parametric Amplification

The paper presents the experimental results of an investigation into a low-noise non-cooled amplification module consisting of the parametric amplifier and the quasi-optical pumping oscillator, intended for implementation as an input circuit of the 60 GHz wave band receivers. The coaxial waveguide resonator was used as an idler frequency loop of the parametric amplifier, while the quasi-optical sphere-corner-echelette open resonator was used as the same for the oscillatory circuit of the pumping oscillator. The experimental results for the model of amplification module, which is executed using the unpacked Schottky-barrier diode and IMPATT diode, are provided. The gain is no less than 16 dB within the 1 GHz bandwidth and the noise temperature is no more than 550 K.     

Reversible transitions in high - Tc cuprates based point contacts

The influence of electric fields and currents has been investigated in the high- superconductors YBaCuO and BiSrCaCuO using a point-contact geometry with Ag as the counterelectrode, which reveal switching transitions between states of a different resistance. The origin of this effect in point contacts is associated with electromigration of the oxygen, driven by the electric field as well as by the current-induced “electron wind”. The switching effect preserves its basic features at elevated temperatures up to room temperature and in high magnetic fields up to 10 T. Received 23 November 1998     

Millimeter wave band open resonators with additional restriction of resonant space

Electromagnetic characteristics of open resonators with a bounded region beside one of the mirrrs are presented. The unknown previously modes are studied and classified. It is the quasi-fundamental modes, associated modes and echelette-echelette oscillations. This result may be used for the applicaiton in the elaboration of oscillation systems of mm-wave devices.     

Low-Noise Semiconductor Amplifier of Middle Part of Millimeter-Wave Range

To decrease the loss of a parametric two-circuit amplifier is a main problem of paper. The use of dielectric inserts with inclined face as a circuit of non-load frequency is considered in the study. Results of electrodynamic simulation of oscillatory processes in a dielectric insert in a rectangular waveguide are represented. Experimental amplitude and noise characteristics of the breadboard model of the parametric amplifier on the basis of the considered filter are given. Within the range of 60 GHz the amplification factor no less than 12 dB over a half-power bandwidth of 1.2 GHz has been obtained with a noise temperature of 550 K.     

Spectroscopy of phonons and spin torques in magnetic point contacts

Phonon spectroscopy is used to investigate the mechanism of current-induced spin torques in nonmagnetic/ferromagnetic (N/F) point contacts. Magnetization excitations observed in the magneto-conductance of the point contacts are pronounced for diffusive and thermal contacts, where the electrons experience significant scattering in the contact region. We find no magnetic excitations in highly ballistic contacts. Our results show that impurity scattering at the N/F interface is the origin of the new single-interface spin torque effect.     

Application of intracellular microelectrophoresis to analysis of the influence of the low-level microwave radiation on electrokinetic properties of nuclei in human epithelial cells

Intracellular microelectrophoresis was applied to investigate the electrokinetic properties of human buccal epithelium cell nuclei after exposure of cells to microwaves of wavelengths of 8 mm (f = 37.5 GHz) and 16 mm (f = 18.75 GHz) at a surface power density of 0.2 mW/cm(2). Irradiated or nonirradiated cells were suspended in a flat microelectrophoretic chamber and exposed to an electric field of 15 V/cm at a current flow of 0.1 mA. The cells, whose nuclei altered their intracellular location towards the anode of the externally applied electric field, were considered to have negatively charged nuclei. The percentage of cells with electrophoretically movable nuclei was determined as the value of electronegativity of cell nuclei (ENN). Microwaves induced changes of ENN during irradiation of 15-60 s. If cells of a donor had an elevated initial level of ENN, it decreased during irradiation. On the contrary, if cells of another donor had a low initial ENN level, irradiation induced ENN increase. No significant difference between the action of microwaves of wavelengths of 8 mm and 16 mm was found. However, microwave irradiation caused an increase in membrane permeability for the in vivo dye indigo Carmine in cells of all donors irrespectively of the initial levels they showed. This suggests that electrokinetic properties of nuclei in cells do not only depend on cell membrane permeability.