In this paper, the method of binary data transmission and receiving is first suggested and experimentally investigated. The method uses dynamical chaos as a source of multiple carrier frequencies. On the server side, the transmitter configures informational signal in the form of frequency grid with chaotically varying frequencies of the spectrum with their amplitudes corresponding to transmitted information message. On the client side, the transmitted information is re-stored using chaotically selected spectral windows. Synchronization of the server and client dynamic chaos generators is achieved by means of TCP/IP protocol. Suggested method is based on combined transmission of information message via transmission channel and background signal. Power of background signal significantly exceeds power of informational one. The method allows using different informational signal as a background signal, such as voice message. The addition of low power chaotically formed frequency grid signal does not lead to significant background signal formation either in spectral or in time domain. Thus, the described method allows repeated application of the transmission channel. The effect of signal-to noise ratio of the order of the filter implementing the spectral windows in the receiver and the width of the spectral window is investigated. Signal-to-noise ratio can be reduced with increasing filter order and spectral window width.

The article considers the method of thermal stabilization for precision power supply output voltage by means of anisotropy of the construction thermal field. Interdependency between schematic and design-topological aspects of precision power supply temperature assurance is shown. In theoretical part of the paper, the concept of electronic component local group arranged on isothermal line of the supporting structure plane is introduced. The local group characteristics and conditions for ensuring topological thermocompensation are formulated. The authors propose the solution for two basic applied problems that provides temperature stabilization of electronic devices output parameters by topological temperature compensation using regression analysis. The experimental part of the paper provides the analysis of the output voltage temperature stability for two design versions which differ by availability of topological thermocompensation. The reason of foreign element base use for the purposes of the experimental part of the study is explained. It is shown that the global mathematical model for providing topological thermocompensation for a design option with improved temperature stability is the temperature error equation. A comparative analysis of the two construction options shows 8 % improvement of output voltage temperature stability due to topological thermocompensation. The obtained result may prove to be satisfactory under technical assignment for the use of a different element base and / or other methods of thermal stabilization.

The ring-slot-element cell for reflectarray antennas is investigated. The mathematical model of the unit cell is based on the integral equation that is solved by the moment method with the use of the spectral domain Green’s function. Coaxial-line higher modes expressed in terms of cylindrical functions are used as the basis for magnet-current representation. It is shown that “stricken” frequencies at which resonance modes occur are an inherent part of slot elements. These frequencies are determined by the Green’s function poles. Moreover, the lowest resonance mode may occur in the operating band under certain conditions. Reflection-phase dependencies on the ring-slot size are provided, demonstrating that at “stricken” frequencies the unit cell does not operate properly. Field plots are presented, which show that the resonance-mode field distribution on the ring slot is significantly different from the normal-mode field distribution. It is found that the “stricken” frequencies might be shifted beyond the operating band by means of thorough selection of unit-cell geometric parameters.

Perfect knowledge of dielectric parameters is necessary for its application in various devices. In spite of the whole range of measurement techniques, their practical implementation in the microwave frequency band runs into some difficulties. This article describes a new method for nonmagnetic dielectrics permittivity and loss tangent measurement in the microwave frequency band. A dielectric specimen slab is placed in the short-circuited waveguide section normal to its axis and fills the whole cross-section of the waveguide at approximately quarter wavelength from its short-circuited endpoint. By means of the vector network analyzer the waveguide section reflection factor is measured. Objective function is de-termined as difference between calculated and measured module and phase of the reflection factor. Specific code for ob-jective function calculation and its minimization is worked out. Minimization of this function by varying dielectric parameters makes it possible to find real values of these parameters. The method needs no de-embedding and can be used with non-calibrated waveguide-to-coax transitions. Also it is less sensitive to the noise component of reflected signal. The testing results show that new method’s error does not exceed 0.2 % for relative permittivity and 1% for dielectric loss tangent.

The paper provides experimental and theoretical study of pHEMT heterostructures with quantum well (QW) AlGaAs/InGaAs/GaAs and delta-doped layer used as active layers for fabrication of 4-18 GHz transistors. As the experimental techniques, the electrochemical capacitance-voltage (ECV) profiling and other methods of admittance spectroscopy are applied. Modernization of commercial ECV-profiling setup allows observing for the first time the concentration peak from a near-surface delta-layer of pHEMT heterostructures together with the enrichment peak from the quantum well. In order to optimize the etching speed the crater bottom control is performed by means of AFM. The electrolyte-semiconductor contact capacitance is measured with Agilent RLC-meter. The main theoretical technique used in the research is numerical modeling of nanoheterostructure key electronic features by self-consistent solution of Schrödinger and Poisson equations. The potential line-up for the conduction band bottom is obtained, and the quantized energy levels are calculated. The complex analysis of series of samples is carried out in order to understand the influence of delta-layer position on the level depth and at the carrier concentration. The optimum distance between QW and delta-layer providing the most efficient charge carrier delivery to quantum well is found. The performed research is aimed at improvement of microwave electronic devices allowing increase of the gain coefficient and the transfer characteristic of SHF-transistors.

The article is devoted to the modeling of a two-bit pin-diode. The possibility of programming opening time of the device based on the pin-diode is shown. The design consisting of a pin diode and two floating gates on the surface of i-region is considered. The addition of electrodes to the surface of the i-region makes it possible to regulate the concentration of electrons and holes within the larger limits in compare with the single-gate structure creating enriched and depleted are-as in the structure. Programming is carried out by applying the appropriate voltage to the control electrodes of the floating gates. It is shown that the charge generated on the floating gate changes characteristics of the i-region of the pin diode.
The key elements of complex simulation of the two-gate pin diode are simulation of charge accumulation mechanism on the floating gate, simulation of pin-diode opening time and calibration of numerical model. Simulation is performed in Synopsys Sentaurus TCAD. Physical models describing traps and their parameters, particle tunneling, transport phenomena in dielectrics and amorphous films are used in simulation. As a result of modeling, the opening time dependences on size, floating gate location and floating gate charge magnitude are obtained.
It is shown that the pin-diode 2-gate structures allow to change the opening time in a wider range than the single-gate ones. To program a large range of pin-diode opening times, it is 2 gate structure that is advisable to use. The obtained results indicate that it is possible to implement a two-bit programming pin-diode and expand its functionality.

The results of experimental research of models of antennas hydroacoustic system (HAS), containing transducers of the waveguide type (TWT), which represent a coaxial set of identical water-filled piezocylinders, electrically excited by the principle of a traveling wave formation in the inner cavity of the TWT, are given. Possibilities of the TWT are analyzed when they are excited in accordance with the solution of the synthesis problem for the investigated HAS. The realization of such excitation is carried out by means of software-controlled multichannel blocks and allows providing a close to uniform amplitude-frequency characteristic of radiation and linear phase-frequency characteristic of radiation in a 3-octave frequency band. The possibility of radiation in this band of ultrashort pulses, tunable in frequency, as well as the formation of signals similar to the signals of cetaceans, is shown. The influence of the number of active piezocylinders of the TWT and the character of its electric excitation on the frequency and impulse response of the investigated HAS is considered. Directional properties of models of antennas HAS, including scanning and pulse operation modes, are considered. A comparative evaluation of the calculated and experimental data, as well as an evaluation of the efficiency of the TWT radiation, is given.

Continuous and steady running of health status remote monitoring systems is essential not to omit episodes of acute exacerbation of chronic disease. Running time of such systems is largely determined by performance capabilities of the patient's wearable system elements. To ensure its long-term operation and efficient performance, the monitoring system must have multilayered structure with the elements realizing recording and picking off biomedical signals, signal processing and analysis, estimation of patient current condition, dynamics of the disease and its prognosis. For this purpose, it is necessary to use smart monitoring algorithms. A specific feature of such algorithms is change of the number of channels used for biomedical signal recording and processing according to the change of patient’s condition. To detect the exacerbation first symptoms by means of the patient's wearable computer, additional channels are activated for recording biomedical signals used to evaluate the expanded complex of diagnostically significant parameters of the disease and their integration when specifying the patient's condition. The system and intelligent monitoring algorithm is tested with the use of heart rate remote control and atrial fibrillation episode detection system. The testing results of the developed system and algorithm are discussed.