Представлены результаты разработки радиометрического комплекса для астрономических и атмосферных исследований в 3-миллиметровом диапазоне длин волн. Радиометр собран по модуляционной схеме с механическим обтюратором, реализованным на сверхразмерных квазиоптических волноводах. В качестве антенной системы использована антенна Кассегрена с диаграммой направленности 1° по уровню –3 дБ. Калибровка осуществляется по встроенному генератору шума. Для наблюдений в выделенной области небесной сферы приемная часть комплекса вместе с антенной размещена на двухкоординатном опорно-поворотном устройстве. Управление, сбор и обработка экспериментальных данных осуществляются в удаленном режиме с помощью разработанного авторами программного обеспечения.

— A radiometric complex for astronomical and atmospheric research in the 3-mm wavelength range has been developed. The radiometer is assembled according to the modulation scheme with a mechanical obturator based on oversized quasi-optical waveguides. A Cassegrain antenna with 1° far-field pattern at a −3 dB level is used as the antenna system. Calibration is carried out using a built-in noise generator. The receiving system of the radiometer, together with the antenna, is placed on a two-coordinate turntable for observations in a selected region of the celestial sphere. Control, as well as capture and processing of experimental data, are performed remotely using the developed software.

A conservative model is proposed for a weakly conductive material medium with changing thermodynamic characteristics during the propagation of a pulse in it. Equations are obtained that describe the change in the shape of the profile of a video pulse propagating in a medium, as well as in nonlinear transmission lines with a temperature dependence of the permittivity. It is shown that if the temperature coefficient of the permittivity is negative, then the peak power of the pulse can increase with time; otherwise, the temperature dependence of the permittivity leads to an increase in attenuation.

The features of the technology of experiments on the non-thermal action of high-power nanosecond pulses are considered on the example of a setup used to modify biological media and other objects with heterogeneous electrophysical characteristics. An experimental setup has been created to study the non-thermal effect of high-power pulses on samples of various materials, which generates pulses with a repetition rate of up to 500 Hz, an amplitude of up to 60 kV, and a duration of 5 ns. The simulation of transient processes in the equivalent electrical circuit of the load was carried out, and the biological material placed in the microplate was used as the load.

Experimental results on the non-thermal effect of powerful electromagnetic pulses of nanosecond duration on grain pests are presented. The possibility of the death of most insects is shown.

The noise immunity of a ring generator consisting of an odd number of inverters based on MOSFET transistors has been studied. Cases are considered in which the effect of interference is reduced to a phase jump of the meander of generator oscillations. An analytical formula for this phase jump is obtained. The correspondence of the analytical formula to the results of the numerical experiment is shown.

The dependence of optical coefficients of ultrathin copper films 2-30 nm thick on the substrate thickness has been studied. Films were fabricated on quartz substrates 4 mm thick, and the thickness of the substrates (6 and 8 mm) was varied by tightly pressing clean substrates with thicknesses of 2 and 4 mm to a 4 mm substrate with a film. The measurements were carried out in a waveguide in the frequency range 8.5-12.5 GHz in the TE 10 mode for two film orientations with respect to direction of the incident wave. The dependences of the optical coefficients measured when the wave was incident from the side of the film and from the side of the substrate differ significantly. It is shown that the effect of anomalously high absorption of waves (more than 77%) by copper films no thicker than 10 nm is observed in a wide frequency band. The maximum absorption (77.5%) was obtained at frequency of 8.5 GHz when a wave was incident on a film 8.6 nm thick from the side of a 6-mm substrate. The effect of extremely low reflection (0.06%) was recorded for the first time when a wave of frequency 11.54 GHz was incident on a film 7.9 nm thick from the side of a 4-mm substrate. It is shown that the frequency range where the effect of minimal reflection was observed exceeds the antireflection band of a dielectric plate with half-wave resonance. Keywords: ultrathin cooper films, quartz substrate, optical coefficients, waveguide measurements, microwave frequency range.

The dependence of optical coefficients of ultrathin copper films 2 – 30 nm thick on the substrate thickness has been studied. Films were fabricated on quartz substrates 4 mm thick, and the thickness of the substrates (6 and 8 mm) was varied by tightly pressing clean substrates with thicknesses of 2 and 4 mm to a 4 mm substrate with a film. The measurements were carried out in a waveguide in the frequency range 8.5 – 12.5 GHz on the TE10 mode for two film orientations with respect to direction of the incident wave. The dependences of the optical coefficients measured when the wave was incident from the side of the film and from the side of the substrate differ significantly. It is shown that the effect of anomalously high absorption of waves (more than 77%) by copper films no thicker than 10 nm is observed in a wide frequency band. The maximum absorption (77.5%) was obtained at frequency of 8.5 GHz when a wave was incident on a film 8.6 nm thick from the side of a 6-mm substrate. The effect of extremely low reflection (0.06%) was recorded for the first time when a wave of frequency 11.54 GHz was incident on a film 7.9 nm thick from the side of a 4-mm substrate. It is shown that the frequency range where the effect of minimal reflection was observed exceeds the antireflection band of a dielectric plate with half-wave resonance.

In a system that simulates aquatic biological media, the possibility of activating nanocomposite liposomal capsules (NLCs) containing spherical electrically conductive nanoparticles on the outer and inner surfaces of the liposomal membrane, using an external ultrashort electric action, has been shown. The decapsulation effect was registrated by fluorimetry methods. The key role of conducting nanoparticles in increasing the sensitivity of NLCs to external ultrashort electrical impact is shown. A theoretical model of nonthermal interaction of NLCs with ultrashort electric pulses is constructed, within the frame of which an expression is obtained for the critical value of the electric field strength, which determines the threshold for the appearance of the decapsulation effect in a conducting medium. The described mechanism of decapsulation explains the selective nature of ultrashort pulsed electrical impact on the NLCs.

We report on the approximate boundary conditions obtained for the problem of calculating the optical coefficients of a system consisting of a dielectric substrate and an inhomogeneous ultrathin metallic film with an arbitrary thickness dependence of the conductivity deposited onto this substrate. The boundary conditions have been derived on the basis of the Picard’s method of successive approximations. Analytical expressions for estimating the error of the calculation of the optical coefficients obtained using the proposed approximate boundary conditions are presented. It is shown that the error increases with frequency and film thickness. The maximum error for 10-nm-thick films is no larger than 10.7% at a frequency of 1 THz. As an example, the complex optical coefficients of a system like the Fabry‒Perót etalon and a metallic film without a substrate with the model thickness dependence of the conductivity have been calculated. The coincidence of the results of the calculations performed by the numerical simulation and using the approximate boundary conditions is shown. The possibility of direct calculation of the average conductivity of a film using the experimental reflectance and transmittance is demonstrated.

The measurements of the reflection and transmission coefficients of platinum films with thicknesses of 1–30 nm fabricated on quartz substrates using magnetron sputtering are reported. The measurements were conducted in a rectangular waveguide at frequencies of 9–11 GHz. For a wave falling onto the Pt film from the quartz substrate side (Q‒Pt orientation), the growth of the absorption coefficient (Amax = 0.45) and the presence of a pronounced minimum of the reflection coefficient (Rmin = 0.23) for the 3-nm-thick film have been observed. In films thinner than 10 nm, the values measured are consistent with the calculations performed with the model thickness dependence of conductivity. The specific conductivity of the Pt films as a function of thickness has been calculated using the approximate boundary conditions and the measured reflection coefficients.

The influence of electromagnetic impulse interference on operation stability of clock generators is theoretically studied. The Van der Pol oscillator is used as a mathematical model of the generator. An abrupt change in the meander phase of generated oscillations is occurred under the influence of impulse interference. An analytical method has been developed that makes it possible to distinguish a certain class of interference, under the influence of which the magnitude of the phase shift depends on the amplitude and duration of the interference. It is shown that the magnitude of the phase shift strongly depends on the section of the self-oscillation meander, which is affected by the noise. This dependence is explained within the proposed analytical approach.

Approximate boundary conditions for a problem of calculating the optical coefficients of a system composed of inhomogeneous ultrathin metallic film with an arbitrary thickness dependence of conductivity deposited on dielectric substrate are obtained. The derivation of the boundary conditions is based on the Picard method of successive approximations. Analytical expressions for the errors in calculating the optical coefficients with use of the proposed approximate boundary conditions are presented. It is shown that the error increases with the frequency and the film thickness increasing. The maximum error for films of 10 nm-thickness does not exceed 10.7% at 1 THz. As an example, the complex optical coefficients of a system similar to Fabry-Perot etalon and a metal film without a substrate with model thickness dependence of conductivity are calculated. The coincidence between the results of numerical simulation and calculations performed with approximate boundary conditions is shown. The possibility of direct calculating the average conductivity of a film from experimentally measured reflection and transmission coefficients is demonstrated.

Nanocomposite liposomes with modified structure containing functional conducting nanoparticles bound to both inner and outer surface of the liposomal membrane are fabricated. Effect of ultrashort electric-field pulses with a duration of less than 10 ns and a field strength of about 10 kV/cm on an aqueous suspension of the liposomes containing encapsulated model substance (NaCl) leads to decapsulation and a corresponding increase in the conductivity of the aqueous medium. Selectivity of the effect is provided by the presence of functional nanoparticles on both surfaces of the liposomal membranes. A theoretical model of a nonthermal effect of ultrashort electric pulses on the nanocomposite liposomes with modified structure is proposed to account for destruction of the liposomal membrane.

The reflection, transmission, and absorption coefficients of ultrathin copper films on a quartz substrate in a waveguide at frequencies of 9–11 GHz were measured. Films less than 5 nm thick are almost completely oxidized and transparent to microwave radiation. A conductive layer is formed when the film thickness exceeds 5 nm, however, the reflection coefficient increases with a thickness in the range of 5-15 nm more slowly than it follows from calculations utilized the model conductivity of a continuous film. The results can be explained by the morphology of the films.

Optical properties of silver nanofilms on its thickness and mechanical deformations in visible and infrared ranges are studied theoretically. The deformation of the film during its elongation leads to a rearrangement of the structure of a surface layer and the appearance of dislocations. It is shown that 9% elongation is crucial for the six monolayer silver film. Mechanical deformations change the electronic structure of atoms in a film, which leads to a significant change in their optical properties. Stretching of the film shifts the absorption peak to the long wavelength region and leads to a slight decrease in absorption. The effects are explained by the significant transformation of the electron structure of deformed silver nanofilms.

The results of precision measurements of the rate of breakdown development in air at atmospheric pressure in the tip–plane electrode system are presented. It is shown that breakdown begins when the threshold voltage Uthr is reached. The higher its value is, the larger is the radius of the tip electrode; a breakdown development rate of 6.2 mm/ns is practically independent of the radius of the tip electrode and is the same for pulses with peak voltages of 25–30 kV. Visualization of the discharge structure with an aluminum film 4 nm thick showed the presence of a large number of microchannels with sizes ranging from 5 to 20 μm.