SIW technologies are becoming more and more popular and relevant. It allows you to significantly reduce the weight and size parameters of the devices, and the accuracy of the devices is practically no different from full-size analogues. So In this paper, we will consider studies of filters of the 3rd, 5th and 7th orders, made using SIW technology. Computer models, theoretical calculations and their comparison with filters made according to these models are presented. The paper also presents a band-pass filter made in a multilayer design
A structural schematic and operating principle of the internal quantum efficiency meter of InGaN LEDs are presented. The operation of the device is based on the method of measuring the internal quantum efficiency, which consists in measuring the emission power and the 3 dB frequency of the LED electroluminescence at two currents in the range from 10 μA to 100 μA and calculating the value of the internal quantum efficiency according to the given formula. The results of measurements of the internal quantum efficiency of various types of commercial LEDs are presented. It is shown that the distribution of LEDs by the value of the internal quantum efficiency is more uniform than the distribution by the value of the emission power, which is explained by the difference in the light extraction efficiency from the active region of the LEDs of the studied samples.
Excitation of magnetostatic waves in a yttrium iron garnet film by a short-circuited SMA transducer, whose thin linear jumper connects the central conductor to an external grounded coaxial cylinder, is considered. The frequency dependences of the return loss for yttrium iron garnet films of different thickness with different orientation of the transducer thin linear jumper relative to the applied external constant magnetic field direction are measured. The cases of the presence and absence of a distance between the transducer and the film are investigated.
Both inverse spin Hall effect (“interface”) and electron drag by magnons (“bulk”) mechanisms of the electromotive force generation by travelling magnetostatic surface (MSSW) and backward volume (MSBVW) waves in YIG/Pt and YIG/n-InSb microstructures are studied. It is shown that “interface mechanism” plays the main role in YIG/ Pt bilayers, while for YIG/n-InSb structures, electron drag by magnons dominates. Giant oscillations of the voltage caused by inverse spin Hall effect were observed in YIG/Pt structures at frequencies corresponding to resonance interactions of MSSW with the volume exchange modes.
The paper presents a block diagram and describes the principle of operation of a measuring complex for photoelectric diagnostics of semiconductor structures with local photoexcitation. The complex allows scanning the working surface of a semiconductor structure with laser radiation, as well as detecting recombination radiation from the surface of a semiconductor structure in the near infrared wavelength region. The results of experimental tests of the complex on a four-quadrant photodiode are presented. The degree of inhomogeneity of the photoresponse can be used to assess the quality of the structure under study and the spread in the sensitivity of the elements of the photodiode under study.
The article presents a mathematical model for assessing the influence of technological deviations of the geometric parameters of permanent magnets on the TWT parameters. The technique proposes to produce through the assessment of the influence of deviations on the magnetic coefficient, as well as the sensitivity of the magnetic field according to the corresponding geometric parameter of the annular magnet. A computer program is presented that implements the described methodology for assessing the impact of technological deviations.
It is proposed to use projections in the form of a hyperboloid surface at the end of the interaction area to increase the electron efficiency of a planar monotron. It is shown that the hyperboloid surface is an effective concentrator of the electric field. Numerical modelling has determined the normalized values of the size of the interaction area and the electrical regime, providing the values of the electron efficiency for the first zone of 35%, for the second - 38% and for the third - 40%.
Detecting a desired signal from noise is one of the urgent problems of signal processing. In this paper a new method is proposed for detecting the breakdown of the average change in the sequence of current values of the thermal activity coefficient for a polymer material during thermal exposure, including using microwave radiation. The proposed method is very effective and easy to implement in practice.
The need to create chamber-type microwave defrosters with a capacity of up to 400 kg/hour was been shown. The results of domestic chamber microwave defroster DMK-10 upgrading with a microwave power of up to 12 kW are presented. The working chamber of the defroster operates in multimode mode with antenna nodes of microwave power. The installation is powered by four magnetrons magnetron M-176 with a microwave power of up to 3 kW at a frequency of 915 MHz. Upgraded antenna nodes for entering magnetron power are placed in the upper surface of the working chamber and on the back wall under the rotating loading table. This arrangement of antennas are ensures uniformity of product warming. Operation comparison of previously existing and upgraded antennas is given. The performed tuning of the antenna power input nodes allowed us to obtain the values of the VSWR and transition attenuation coefficients between the antennas required for magnetrons operation. The ergonomics of loading meat and fish blocks was improved. The design of upgraded defroster is changed. Studies of the modernized installation operation in the conditions of food industrial production are carried out on the territory of the customers. Experiment show that the operational characteristics of the upgraded defroster correspond to the parameters of the foreign defrosters.
The purpose of the research is to propose block diagrams of the elements of the measuring complex, which is designed for fire-fighting monitoring of natural areas. Four basic elements schemes of the measuring complex have been formed. The elements include sensors, blocks for primary information processing, blocks for providing information exchange, blocks for autonomous power supply. These elements are designed to collect and transmit information about the state of controlled areas. The topology of the measuring complex is based on the basis of Mesh network principles. Information about the state of controlled areas is sent to the Web-server. On this server, the received information is processed. Based on the results of information processing, recommendations are formed that are intended to provide control actions on certain sections of the controlled territory. The main task of control actions is to reduce the level of fire danger or increase the efficiency of preparatory measures to eliminate the fire. Cellular, trunking, or satellite communications networks are used to interact with information collection devices with a Web-Server. In some cases, an unmanned aerial vehicle may be used to collect information.
Computer models of spectrum analyzer and signal modulators have been created.. These models are included in the virtual laboratory. A laboratory work has been created to study the spectrum of modulated radio signals. The interface of the spectrum analyzer model is completely similar to the real device.
This article deals with new Lange coupler and Marchand balun based on a novel coupled line section. The coupled line section is differ with conductor isolation and increased height to width ratio. A design method for novel Lange coupler and Marchand balun is proposed. The design method was verified through electromagnetic simulation and experimental verification.
The work is devoted to the development of universal modular-block platform for creation of installations with microwave processing. The developed platform is planned to be used for installations of microwave and combined convective drying, thermal disinfection and swelling and calcination of various materials. The development of universal microwave heating unit consisted from 6 magnetrons with a power of 850 watts at a frequency of 2450 MHz has been carried out. The design of the block allows it to be adapted to the conveyor parameters and to processing of various organic and inorganic materials. The design of 6 flat horn antennas assembly is developed and manufactured. The electrodynamic characteristics of horn antennas are measured and adjusted using a vector circuit analyzer. Microwave processing block has been manufactured, including an antenna assembly, magnetrons with power sources and cooling and control systems. Tunnel section is developed to ensure electromagnetic safety. The microwave processing block showed high performance characteristics during tests on conveyor system for drying organic material. The created modular-block platform of the conveyor installation of microwave processing makes it possible to comprehensively solve most technological problems.
Prospective circuits of fast-speed operational amplifiers (Op-Amps) based on a "folded" cascode implemented on silicon bipolar transistors, as well as GaAs JFET and GaAs p- $n$ - $p$ BJT transistors are proposed. Computer modeling of Op-Amps in the LTspice environment showed that the Op-Amp's open-loop gain exceeds 60 dB, and their slew rate (SR) reaches hundreds of $\mathbf{V}/\boldsymbol{\mu \mathrm{s}}$ . The developed operational amplifiers can be recommended for use in analog front-end, used in detectors of various physical quantities for high energy physics, space tools and medicine.
In this work, we studied the sensitivity of porous silicon structures obtained by electrochemical etching to vapors of polar organic compounds.Current-voltage characteristics (CVCs) of the samples were obtained in the presence of vapors of various concentrations of acetone, ethanol, and isopropanol at room temperature. Based on these CVCs, the dependences of the sensitivity on the applied voltage were calculated and analyzed.
The article discusses the features of the construction of gallium arsenide (GaAs) operational amplifiers (OpAmps), as well as their input, intermediate and output stages. OpAmp circuit solutions have been developed that provide low values of the zero offset voltage systematic component (lower than 1 μV) and an increased open-loop voltage gain (155 dB). Mathematical analysis of the main parameters of OpAmp is performed. The results of computer modelling of an OpAmp based on combined GaAs manufacturing process by the OJSC “Minsk Research Institute of Radio Materials”, which implement n-channel FET and p-n-p bipolar transistors, are presented. The GaAs OpAmps considered in the article can be used in various analogue transducer and ADCs (signal transducers, active filters, active front end etc.), including their implementation for the microwave ranges.
This article discusses the calculated values of diffusion and mobility of charge carriers, which characterize the motion of electrons and ions in a low-temperature gas-discharge plasma of inert gases. These parameters make it possible to describe the motion of electrons and ions in a gas-discharge plasma over long (compared to the free path time) times in the presence of an external electric field and without it. Graphs of the mobility of charge carriers in a magnetic field are obtained and analyzed. The article calculates the minimum values of the magnetic field of inert gases, at which low-temperature plasma becomes homogeneous.
This article provides an overview of the cooling methods for modern microwave amplifiers. The object of research is a microwave module that combines a semiconductor amplifier, a vacuum amplifier and a power supply system. A technique for modeling and calculating thermal effects on a microwave and a semiconductor module, as well as thermal calculations for the operation of an amplifier, is presented. This technique will evaluate the efficiency of the cooling system.
Graphene sensor structures were modified by a focused ion beam (FIB) with a selected distance between the points in the central area crossing the channel with a different exposure time per point. An effect of FIB exposure on structural properties in graphene was evaluated by Raman spectroscopy and electrical measurements. The resistive sensor response (SR) of the selected sensors towards water vapor and $\boldsymbol{\text{NH}_{3}}$ exposure outperforms the known results for modified graphene with other techniques. The set of structures demonstrates a specific SR behavior due to the implementation of different gas sensitivity mechanisms when changing the FIB modification time: graphene with a short modification time demonstrates an increase in the SR to NH3 with rising relative humidity (RH), while the SR of graphene with a long modification time decreases with rising RH. Along with the opposite changes in the resistance at SR to water vapor, it allows to correctly determine the concentration of NH3 at different levels of RH at room temperature by the array of only three sensors using linear discriminant analysis (LDA).
