Al. V. Skripal

Measurements of thickness of metal films in sandwich structures by the microwave reflection spectrum

The method for measurements of the thickness of nanometer metal films in sandwich structures by the microwave reflection spectrum had been proposed and implemented experimentally

Frequency dependence of the coefficient of microwave radiation reflection from magnetic fluid at liquid nitrogen temperatures

The coefficient of microwave radiation reflection from a plane layer of a magnetic fluid magnetized by a magnetic field of 11.5 kOe is measured in the temperature range 253–293 K. The concentration of the magnetic phase (magnetite) is 15 vol %. In this temperature range, the dynamic susceptibility of nanoparticles exhibits strong dispersion (ferromagnetic resonance). Experimental data are treated by invoking the theory of high-frequency magnetization of an ensemble of interacting isotropic superparamagnetic particles. It is shown that, when the temperature drops below the room value, the trends observed at elevated temperatures (a decrease in the fraction of the power reflected from the magnetic fluid and an increase in the frequency of a minimum in the frequency dependence of the power) are retained.

Temperature Dependence of the Coefficient of Reflection of Microwave Radiation from a Magnetic Fluid Layer

The coefficient of reflection of microwave radiation from a plane layer of a magnetic fluid magnetized in a field of 11.5 Oe is measured in a frequency range of 24 MHz in temperature intervals 293–333 K; the volume concentration of the magnetic phase (magnetite) is 15 vol %. In this range, the dynamic susceptibility of nanoparticles exhibits strong dispersion (ferromagnetic resonance). The experimental results are interpreted on the basis of the theory of high-frequency magnetization for an ensemble of noninteracting isotropic super-paramagnetic particles. It is found that this simple model provides a satisfactory description of the temperature and frequency dependences of the reflection coefficient.

Determination of the magnetic fluid parameters from the microwave radiation reflection coefficients

The interaction of microwave radiation with a magnetic fluid that completely fills a waveguide and is bounded by a dielectric insertion is studied at frequencies between 20 and 40 GHz. The frequency dependence of the alternating interference maxima and minima that are associated with the reflection from the front and back walls of the dielectric insertion is found. The reason for such a dependence is the variation of the complex magnetic susceptibility of the magnetic fluid. The inverse problem, i.e., the determination of the ferromagnetic particle diameter and the volume content of the solid phase in the magnetic fluid, is solved based on the frequency dependence of the reflection coefficient.

Radiowave interferometry of human thorax displacement, related with breath and heartbeats

In this paper, the application of fixed-frequency and multifrequency radiowave interferometry using magic tee and Gunn-diode autodyne for detection of human respiratory shifts and heartbeats is presented. The methods, which provide remote detection of thorax shifts, caused by respiratory movements and heartbeats, are implemented; amplitudes and frequencies of respiratory movements and heartbeats are measured

Measurement of the parameters of nanometer films by optical and microwave methods

It is demonstrated that the thickness and the electrical characteristics of thin insulator and metal films in layered structures can be determined from the reflection and transmission spectra of optical and microwave radiation interacting with these films. Measurements of the refractive index of SnO2 films in the range of thicknesses 40 nm to 2.8 μm and the electrical conductivity of Cr films deposited on ceramic substrates are reported.

Radiowave interferometry of human respiratory movements and heartbeats

The possibility of applying the fixed-frequency and multifrequency radiowave interferometry with utilization of magic tee and Gunn-diode autodyne for detection of human respiratory movements and heartbeats has been proved.

Synchronization of the heartbeat rate of Daphnia by an external electric field

Experimental investigations were made of the influence of an external alternating voltage on the amplitude and heartbeat rate of Daphnia freshwater crayfish. It was observed that the heartbeat rate of Daphnia was synchronized by an external electric field.

Laser autodyne interferometry of the dynamic parameters of biological specimens

A method based on the use of autodyne detection effects in a semiconductor laser is proposed to analyze the dynamic state of biological specimens. The advantages of this method compared with conventional photoelectric methods are demonstrated. Results are presented of the use of the proposed method to investigate the heart beat frequency and amplitude of Daphnia as a function of the degree of toxicity of the aqueous medium.