Introduction. Modern antenna devices contain a large number of repeating elements. The process of development of CAD models of such devices requires repeatedly performed operations that is a routine task for an engineer. Therefore, the problem of repeating operations automation arises when constructing antenna models with periodic structures.

Aim. To demonstrate the automation of slotted waveguide antennas design process in CAD Ansys HFSS.

Materials and methods. In order to determine the dimensions of the slotted waveguide antenna the energy method was used. Automation procedure of the design of the slotted waveguide antennas in CAD Ansys HFSS using the Visual Basic Scripting Edition macros was presented.

Results. In order to design and edit slotted waveguide antennas in CAD Ansys HFSS four macros in the VBScript language were established: for slot subtraction from a broad wall of a rectangular waveguide at given coordinates; for removing the original slots created using the previous macro; for drawing a polyline passing through the centers of the slots, in order to verify the antenna’s near field realized distribution; for inclined slot subtraction from a narrow wall of a rectangular waveguide at given coordinates. Results of the macros usage were presented.

Conclusion. The above mentioned macros allow one to automate the routine steps during the process of creating and deleting objects while designing an antenna model with periodic structures in CAD Ansys HFSS. Specified procedures for creating macros could be extended to a wide class of tasks related to the studies of characteristics of electromagnetic structures including repeating objects (phased antenna arrays, reflective arrays, slotted waveguide antennas, fractal antennas, log-periodic antennas, multi-layer lens antennas, ladder-type microwave filters).

Introduction. In the paper a fault isolation problem in the devices combining digital unit by functional diagnostics methods is considered. Networks of state automates are accepted as mathematical models of the devices. Assumed, that functional diagnostics devices for each network component are preliminarily constructed in an optimal way and they consist of a control automata and of a fault discriminator of unit dimension.

Aim. To develop functional diagnostics method based on theoretical analysis allowing to decide fault isolation problem in networks of state automation and to reduce computational complexity and hardware redundancy.

Materials and methods. An analysis of mathematical description of a network of state automation and functional diagnostics devices for each network component was presented in terms of algebraic theory of functional diagnosis of dynamic systems. A possibility to transform the set of known functional diagnostics devices of the network was demonstrated. The possibility provided a localization of the network component with an error, if the component was unique.

Results. A searching procedure of the analytical equations determining supervision automata and fault discriminator for the whole network was proposed. The case when initial functional diagnostics devices for each network component were defined by scalar functions was considered. The obtained result was generalized to the case, when mentioned devices were defined by vector functions. The application of the described method was demonstrated in the example of construction functional diagnostics devices for simplified fragment of the device for forming priorities of mutual aircraft navigation system.

Conclusion. Estimation of results by an order criterion was obtained. It was established that with an increase in the number of network components, the reduction of intentioned redundancy by functional diagnostics devices compared with the original version increased significantly.

Introduction. Electromagnetic or ionizing radiation (IO) has great influence for radiation resistance of MOSFETs (metal–oxide–semiconductor field-effect transistors) and integrated circuits. Oxide, for the studied samples, is silicon dioxide, which acts as a dielectric in MOS structure. Currently, in literature there is no unambiguous idea of complete radiation response of MOSFETs to various types of ionizing radiation.

Aim. To study radiation response of MOSFETs under influence of gamma and X-ray irradiation; to study effect of applied external potential of a gate substrate.

Materials and methods. A total dose effect of gamma and X-ray radiation on the threshold voltage of MOSFET with a polysilicon gate and a gate oxide thickness of 120 nm with an applied external potential (-3, -2, 0, 3, 5, 10) V was studied. For gamma irradiation radionuclides cesium-137 with an energy of gamma quanta of 662 keV were used. X-ray tube with tungsten-rhenium cathode operated in modes 40 keV and 90 mkA was used as a source of X-ray radiation. Dose and time dependences of the change in the threshold voltage of n- and pchannel MOSFET were analyzed. It was performed that the influence of gamma and X-ray radiation led to the same effects in the studied structures. The maximum radiation response of MOSFETs was observed at high positive gate-substrate potentials. The approximation parameters associated with the concentration and capture cross sections of traps responsible for the formation of charges in the dielectric gate through irradiation were determined.

Results. Strong influence of gamma and X-ray radiation led to the same effects in the studied structures. The applied voltage to the MOS structure during X-ray irradiation had a strong effect on their radiation response. The maximum radiation response of MOSFET at high positive gate-substrate potentials was observed. Proportionality coefficients to ensure the coincidence of the initial sections of the dose dependences for various applied gate-substrate potentials during irradiation were introduced. The coefficients allowed one to compare active and passive modes of operation of the X-ray emitter. Correction factors depended on the polarity of the applied gate-substrate potential. For negative potential, the proportionality coefficient value was 38.5. For the case of positive polarity the coefficient did not depend on the applied potential and the value was 120.

Conclusion. The study allows one to determine the coefficients for dose dependences of threshold voltage changes. For the first time, to establish a numerical relations between the effects of various types of radiation sources at irradiation doses up to 1.9 · 104 Rad and proportionality coefficients becomes possible. It allows one to take into account the influence of applied potentials during irradiation on the radiation response of MOS structures.

Introduction. Currently, an interest in improving pin-structures continues to be the focus of attention of developers of electronic devices. Devices that use controlled pin-structures include: non-volatile memory, static voltage protection device, pin-diodes with adjustable characteristics, etc. However, insufficient attention is paid to the issue of controlling the characteristics of pin-structures by using discrete metallization on the surface of i-region.

Aim. Investigation of the influence of discrete metallization of the surface of i-region on static and dynamic characteristics of pin-structure, defect compensation, and efficiency control of the pin-photodetector.

Materials and methods. The pin-structure under study consisted of p + -boron-doped region; n + -phosphorusdoped region; i-phosphorus-doped region; semi-insulating substrate; metallization of the substrate; polysilicon control gate; and a silicon oxide dielectric layer. Two-dimensional numerical analysis of the potential distribution, of the concentration of free charge carriers and currents was performed in the Synopsys Sentaurus TCAD environment.

Results. Two-dimensional analysis of discretely metallized pin-structures was performed. The stresses applied to the gates of i-region that compensated the influence of defects formed by electron irradiation were determined. Four pin-photodetector structures were modeled, in which the control gates were performed in the form of metal–dielectric–semiconductor structure. The possibility of increasing the sensitivity of the pinphotodetector by applying the corresponding potentials to the gates was demonstrated.

Conclusion. An effect of discrete metallization of i-region of the pin-structure was investigated. A method for correcting of the characteristics of the irradiated pin-diode to the initial characteristics was proposed. It makes possible to use such diodes in electronics with high requirements for operating in areas with high radiation. The design of a high-sensitivity photodetector with control gates on the surface of i-region and with the structure of low alloy i-region split into two regions (p- and n–type conductivity) was proposed.

Introduction. Acousto-optic spectrum analyzers interferometric schemes have been developed to increase dynamic range. It was assumed that dynamic range, expressed in dB, would double. An expected increase was not achieved yet.

Aim. To analyze the homodyne acousto-optic spectrum analyzer noise characteristics, to estimate the signal-tonoise ratio and the dynamic range.

Materials and methods. A mathematical model was compiled which took into account the need to form quadrature components to obtain an amplitude spectrum of an input signal, shot noise and readout noise.

Results. An interferometric scheme did not allow to achieve dynamic range doubling compared to an acoustooptical power spectrum analyzer. The dynamic range increase was less than 1.35 dB. Constant illumination led to a significant increase of the spectrum analyzer self-noise due to shot noise, compared to which thermal noise and readout noise became insignificant. The spurious-free dynamic range estimation expression was obtained. It was prior determined by acousto-optic interaction nonlinearity. With typical analyzer blocks parameters the spurious-free dynamic range covered a single-signal dynamic range. Signal-to-noise ratio estimation expression was presented.

Conclusion. The homodyne acousto-optic spectrum analyzer single-signal dynamic range is determined primarily by the photosensor saturation charge. One needs to optimize their relation by taking into account light source power, acousto-optical modulator diffraction efficiency and photosensor saturation charge. Presented noise model gives more accurate estimation of the dynamic range with an error of 1 dB.

Introduction. Simple-shaped cavity resonators: rectangular, cylindrical and coaxial, are widely applied in modern microwave engineering in design of different functional devices of middle and high power levels. Parameters of resonators can be obtained analytically by using expressions from literature. Concentric resonators, performed on the basis of classical simple-shaped cavities with a central metallic core represent a new class of electrodynamic systems of microwave range, the properties of which remain poorly studied. One of these structures, named a rectangular concentric resonator (RCR) is proposed in the paper as a basic unit of K-band bandpass filters (18...26 GHz).

Aim. To study potential possibilities of RCR for creation electromagnetic signals filtration devices of micro wave range.

Materials and methods. The finite element method implemented in the package COMSOL was used to investigate electrodynamic characteristics of RCR and scattering matrix parameters of the microwave filters on RCR basis.

Results. Simple polynomial expressions for computation of normalized resonant wavelengths of RCR were obtained at the first stage of modeling. Next, two models of passband microwave filters by RCR with different sizes were built and their EM characteristics were studied. Cavities sizes were determined numerically and practical recommendations on the realization of a new type bandpass microwave filters were formulated.

Conclusion. New results of the finite-element analysis of spectral characteristics of two models of bandpass Krange filters on rectangular concentric resonators were represented. The advantages of the filters were indicated. Simple analytical expressions for calculation of the resonance wavelengths of the considered concentric resonators were obtained.

Introduction. The present stage of development of hydroacoustic equipment is characterized by a constant improvement of an element base and by an increase in computing power. However, in solving of applied problems one is increasingly faced with a restriction on the realized bandwidth of electroacoustic transducers and antennas. The most of well-known methods of bandwidth expansion do not provide a linear character of the phase-frequency characteristic (PFC) of radiation in the working frequency band, which is of primary importance for the effective formation of relatively short, frequency-tunable, and complex acoustic signals. From this position, the use of a transducer of waveguide type (TWT) is preferential. Its construction and electrical excitation method provides a close to linear phase response of radiation.

Aim. The development of a generalized computational model. It has to include particular cases of TWT radiation into cylindrical waveguides coaxial with it and into half-spaces, and also to take into account the influence of waves reflected from the boundaries of the TWT on its field characteristics.

Materials and methods. The TWT was presented by a coaxial set of identical water filled piezocylinders with amplitude-phase excitation, provided a mode of broadband radiation in the form of traveling waves. The usage of the method of partial regions allowed one to obtain a solution of the problem of TWT radiation through water filled apertures into the conical adjacent half-spaces, variable in angle.

Results. Frequency characteristics of TWT sound pressure results calculated in accordance with the solution of the synthesis problem in the frontal and rear directions for different angles of cone opening were presented and analyzed. Using the proposed computational model of TWT, the possibility of obtaining a bandwidth of the order of 3 octaves was demonstrated. An influence of the thickness of the passive flanges, which are used to link the TWT in the antennas was estimated. The possibility of radiation in the working frequency band of TWT of ultrashort ultra-short single-period pulses for different angles of cone opening was considered. A comparative assessment of the result of calculation with other particular solutions (the radiation by TWT in coaxial water-filled waveguides and also – in half-spaces) was presented

Conclusion. An expedient to use a generalized computational model for a more accurate description of the acoustic fields of real antenna models made up of TWT was concluded.

Introduction. Laser correlation spectroscopy is a promising method that allows one to analyze sizes of nanoparticles and to evaluate their shape and dynamics of aggregation in liquids. A limited usage of laser correlation spectroscopy is currently caused by insufficient accuracy of existing instruments and data processing algorithms. The paper described the development of laser correlation spectroscopic hardware complex designed for nanoparticles size determination in liquids. The basic requirements for the elements of the device and the approaches used to calculate the signal-to-noise ratio were discussed. The achieved parameters of the laser correlation spectrometer were presented.

Aim. To develop the hardware for nanoparticles size determination in liquids and to optimize the parameters of hardware elements to increase signal-to-noise ratio.

Materials and methods. Theory of dynamic light scattering to describe scattering of laser radiation in liquids was applied. Fundamental requirements for the elements of the laser correlation spectrometer were described.

Results. An original scheme of the laser correlation spectrometer was developed, the basic requirements for the general scheme elements were described. Equations for calculating signal-to-noise ratio were given.

Conclusion. The analysis of the main parameters of the elements of the laser correlation spectroscopic scheme were carried out. It helps one to evaluate the expected signal-to-noise ratio in laser correlation spectrometers.

Introduction. Cardiopulmonary stress test provides significant diagnostic and prognostic information of the condition of patients with cardiovascular and pulmonary diseases. There is a serious problem, that final phase of stress testing is a physically difficult exercise for a person. There is a significant risk of occurrence and development of pathological conditions of the patient's cardiovascular system. One of the solutions is the development of methods for assessing the biological parameters of the patients at the end of a load protocol based on data from the initial stages of the test.

Aim. Development of a method for finding an estimate of the maximum heart rate (HR) and of the peak oxygen consumption (OC) for the patients with chronic heart failure at the end of a cardiorespiratory exercise stress test, based on the results of the study obtained at the first initial stages of the test.

Materials and methods. For the study, 149 anonymized records of rhythmograms and data of changes in the oxygen consumption of the patients with chronic heart failure were used. The patients underwent a cardiopulmonary stress test by a bicycle ergometer using step-by-step load protocol (the load power increase at each stage was 10 W, the duration of the load stage was 1 min)

Results. Based on the analysis of the data obtained, a method for assessing the peak values of HR and of PC of the patients with chronic heart failure was developed.

Conclusion. The relative error of the proposed estimate of the HR peak in most cases was no more than 10 %, which allows it to be used for practical purposes. It was established that when performing 70 % of the stress protocol, the error of the proposed estimate of the OC peak in most cases did not exceed 20 %. More research is needed to improve the accuracy of the assessment for using in medical applications aimed to the modernization of methods and equipment for stress testing of the patients.