The paper is devoted to the development of a C-band T-junction of circular and rectangular waveguides with ability to adjust the impedance matching. In order for the device to operate at the C-band, the required sizes of the waveguides were selected. Several examples of impedance matching of waveguide junctions are considered. As a result of simulation, the characteristics of the reflection and transmission coefficients, as well as a picture of the field inside the waveguide junction, are built, which show that using a matching window and a capacitive post, good matching of circular and rectangular waveguides can be achieved. Based on the results obtained, a real device was manufactured, the characteristics of which turned out to be close to the expected ones. It is shown that using the design of a device with longitudinal slits along a rectangular waveguide, it is possible to adjust the impedance matching of the device at the desired frequency within the operating range.

The paper presents the results of research and development of a software and hardware model of an artificial lung ventilator (ALV) based on the National Instruments (NI) ELVIS 2 hardware platform and the LabVIEW software development environment. The model is built in accordance with the traditional scheme of modern ALV, consisting of three main parts: a flow generator, a switchgear and a control system. The model implements three modes of artificial lung ventilation – HiFlow, O2 and CPAP with the possibility of supplying pure oxygen and humidifying and heating the respiratory mixture. To control the model and monitoring the current state of the ventilation process, the ventilation parameters are changed by the model operator in real time and displayed on the computer monitor in the software part of the model. The software itself implements medical algorithms for three ventilation modes and control algorithms for system actuators using closed-loops. To expand the possibility of monitoring the ventilation condition, the model implements the transmission of current parameters using an Ethernet network.

The description of a new method for increasing the resolution of radio pulse sensors (RPS) designed for short- range radar systems (SRRS) for detecting and measuring motion parameters of location objects is presented. The essence of the method is that the controlled area of space with the targets located in it is periodically irradiated with probing radio pulses, and during their radiation, radio pulses reflected from the targets are simultaneously received and divided into two quadrature channels. Next, they are mixed with probing radio pulses, and the time-overlapping parts of these radio pulses are converted into the region of low Doppler frequencies in the form of two quadrature video pulses. Then, the quadrature video pulses received in these channels are sampled by amplitude, stored at multiple points in time and digitally processed according to the proposed algorithm. The method is implemented in the RPS made on the basis of a horn-lens antenna, a Doppler receiving and transmitting module with quadrature outputs of converted signals, a synchronization and pulse generation unit, as well as a digital signal processing unit. The RPS can be used in onboard (for example, automotive) SRRS designed to detect moving targets, measure the distance to them, as well as determine the speed and direction of movement. The results of experimental studies have been obtained on the example of the 8-mm autodyne RPS made on the basis of the oscillator on a planar Gann-diode.

The paper describes the design technology for a leaky-wave antenna based on a substrate integrated waveguide that radiates waves at a given angle. Doppler speed measuring devices with improved accuracy characteristics use these antenna types. The presented results for a short antenna are used to adjust the dimensions of the substrate integrated waveguide and radiating slots. The proposed design utilizes the RO3003 substrate. The radiation pattern and the electromagnetic field strength in the near field are presented for electrically long leaky-wave antennas. The amplitude distribution over the antenna surface decreases and distorts the radiation pattern for a structure with uniform periodical slots. The slots are combined into groups with different lengths to equalize the amplitude of the near-field distribution and overcome this drawback. Thus, it is possible to obtain a distribution close to uniform. This paper presents the simulation results of the near-field distribution, directivity, and S-parameters of the optimized antenna structure.

This paper presents the results of a study on the formation of signals from an autodyne short-range radar system with linear frequency modulation for a moving reflecting object. The autodyne signal charts are obtained for cases when the duration of the signal is much longer than the delay of the reflected radiation, as well as for cases when this inequality is not fulfilled. Experimental data were obtained from an oscillator based on an 8-mm Gunn diode, with frequency tuning performed using a variable capacitor.

The description of the device and the principle of operation of a new type of autodyne transceiver of short-range radar systems (SRRS), made on the basis of an optoelectronic oscillator (OEO), is presented. The antenna is connected to the OEO through a dividing-decoupling device (DDD), which provides, on the one hand, conditions for generating self-oscillations in the system and, on the other hand, transmitting and receiving radio signals with minimal losses. The scheme of the DDD and the method of calculating their parameters are considered. A mathematical model of the autodyne system based on the OEO has been developed, and the basic relations for determining its parameters and characteristics have been obtained. It is demonstrated that the use of OEO provides a significant increase in the equivalent Q-factor of the oscillator system and the reduction in its own noise. The improvement of these parameters of the autodyne SRRS will significantly increase the range of operation, expand the range of operating frequencies and the scope of their application. The prospects of using autodynes based on OEO in the creation of detection systems of objects with a small effective scattering area, such as unmanned aerial vehicles, for protection against which the use of conventional (distant) radars is ineffective, are noted.

The description of a new method of signal generation and processing which provides an increase in the noise immunity of radar sensors (RS) with frequency switching (FS) radiation is presented. The principle of method is in the use of a set of time intervals when measuring the phase difference of signals at different radiation frequencies and, accordingly, a set of the Doppler frequency values in the signal spectrum when determining the average value of the Doppler frequency, as well as the use of forward and reverse IF sequences. This method allows averaging the results of calculating individual implementations and, thereby, increase the accuracy of determining the target speed and distance to it. At the same time, the stability of the RS with FS also increases to the effects of signals from third-party radio sources and interference from the underlying surface. The results of experimental studies of the method are obtained on the example of the autodyne RS with the 8-mm frequency range, made on the basis of the Gann diode generator with frequency control by varicap. The method may be used in on-board (for example, automotive) radar sensors designed to detect moving targets, measure the distance to them, as well as determine the speed and direction of movement.

Представлены результаты анализа сигнальных и шумовых характеристик автодинов с частотной модуляцией. Математическая модель автодина представлена в виде автогенератора с одноконтурной колебательной системой, перестраиваемой по частоте изменением емкости варикапа. Учтено воздействие на автогенератор собственного, отраженного от объекта локации излучения, и внутренних шумов генератора. Исследована зависимость степени искажения сигнальных характеристик и периодическая нестационарность среднеквадратичного значения уровня частотных и амплитудных шумов в зависимости от расстояния до объекта локации, и величины параметра внешней обратной связи автодинной системы «генератор—объект локации». Показано, что при малой величине параметра внешней обратной связи сигнальные характеристики являются квазигармоническими, аналогично системе гомодинного типа, а шумы представляют собой стационарный случайный процесс. При величине параметра внешней обратной связи, соизмеримой с единицей, у сигнальных характеристик наблюдаются ангармонические искажения, а у шумовых — наличие периодической нестационарности. Установлено, что с увеличением расстояния до объекта локации, когда время запаздывания отраженного излучения становится соизмеримым или больше периода автодинного отклика, степень ангармонических искажений сигнальных характеристик и высота пиков среднеквадратического уровня шума значительно уменьшаются. Результаты экспериментальных исследований получены на опытном образце автодинного датчика с частотной модуляцией, выполненного на диоде Ганна 8-мм диапазона.

The paper presents the results of analysis of signal and noise characteristics of autodynes with frequency modulation. The mathematical model of autodyne is presented in the form of a self-oscillator with single-loop oscillation system that is frequency-tuned using the varicap. This model takes into account the impact of intrinsic radiation reflected from location object and the impact of generator internal noises on the oscillator. The paper investigates the relationship of the distortion degree of signal characteristics and the periodic nonstationarity of the root-mean-square value of the level of frequency and amplitude noises as a function of the distance to the location object and the value of external feedback parameter of the autodyne “generator–location object” system. It has been shown that at a small value of the parameter of external feedback, the signal characteristics are quasi-harmonic similar to homodyne type systems, while noises represent a stationary random process. If the value of external feedback parameter is comparable to unity, anharmonic distortions are observed in signal characteristics, while the periodic nonstationarity is observed in noise characteristics. It was established that with an increase of distance to the location object, when the delay time of reflected radiation became comparable or larger than the period of autodyne response, the degree of anharmonic distortions of signal characteristics and the height of peaks of root-mean-square noise level were significantly reduced. The results of experimental investigations have been obtained using the prototype of autodyne sensor with frequency modulation built on the 8-mm band Gunn diode.

Представлено описание нового метода формирования и обработки сигналов, обеспечивающего повышение помехоустойчивости радиолокационного датчика (РЛД) с переключением частоты (ПЧ) излучения. Суть метода состоит в использовании множества временных интервалов при измерении разности фаз сигналов на разных частотах излучения и, соответственно, множества значений доплеровских частот в спектре сигнала при определении среднего значения доплеровской частоты, а также применения прямой и обратной последовательностей ПЧ. Данный метод позволяет усреднить результаты вычисления отдельных реализаций и, тем самым, повысить точность определения скорости цели и расстояния до нее. При этом также повышается устойчивость РЛД с ПЧ к воздействию сигналов от сторонних источников радиоизлучения и помех от подстилающей поверхности. Результаты экспериментальных исследований метода получены на примере автодинного РЛД с ПЧ 8-мм диапазона, выполненного на основе генератора на диоде Ганна с управлением частоты варикапом. Метод может найти применение в бортовых (например, автомобильных) радиолокационных датчиках, предназначенных для обнаружения движущихся целей, измерения расстояния до них, а также определения скорости и направления движения. Носков В. Я., Богатырев Е. В., Игнатков К. А., Черных О. А., Шайдуров К. Д. Метод повышения помехоустойчивости радиолокационных датчиков с переключением частоты. Ural Radio Engineering Journal. 2021;5(3):284–304. DOI: 10.15826/urej.2021.5.3.006.

The results of the study of the features of the formation and processing of signals of autodyne short-range radar systems (SRR) with frequency modulation (FM) involving non-linearity of the modulation characteristic are presented. The numerical simulation of the nonlinear influence of the modulation characteristic on the shape and spectrum of the autodyne signal is implemented on the basis of the mathematical model of the autodyne generator. We have established that even a small non-linearity of this characteristic causes a significant distortion of the shape and spectrum of the autodyne signal. A method of quasi-static correction of the law of frequency modulation of probing radiation using a digital signal processor is proposed, which does not require complication of the microwave part of the autodyne SRR with FM. The results of experimental studies of an 8-mm autodyne SRR made on the basis of a Gann diode oscillator with frequency control by varicap are presented.

A mathematical model of an autodyne oscillator with a combined amplitude-frequency modulation, which is under the influence of its own radiation reflected from the target, is developed. The main relations are obtained for analyzing the autodyne response of a single-circuit oscillator depending on the delay time of the radiation reflected from the target with an arbitrary law of simultaneous amplitude and frequency modulation. The characteristics of the amplitude selection of signals, as well as their temporal and spectral characteristics, are calculated for harmonic amplitude-frequency modulation. The features of signal formation are established for various values of the amplitude and frequency modulation parameters and the feedback parameter of the "oscillator-target" autoparametric system. The results of experimental studies, performed on a Tigel-0.8M hybrid-integrated Ka-band oscillator module with a Gann mesa-planar diode, confirmed the findings of the theoretical analysis.

A description is given of new principles for constructing autodyne sensors intended for non-contact measurement of deviations from the nominal value of the internal dimensions of metal products using millimeter-wave radiation. The proposed sensors are distinguished by the simplicity of the design of the measuring head and low cost. They use a single, but multifunctional device, a microwave autodyne, as a transmitter of probe radiation and a receiver of radiation reflected from the inner surface of the product. Sensors that implement the proposed construction principles can be used in the machine-building, pipe-rolling and chemical industries to control the inner diameter of pipes during their production, as well as ovality and wear during operation of pipelines. Experimental data were obtained on the Ka-band Gunn-diode autodyne sensor.

Представлены результаты исследований особенностей формирования сигналов автодинных систем ближней радиолокации с комбинированной амплитудно-частотной модуляцией. Получены выражения для расчета автодинных сигналов одноконтурного генератора с произвольным законом одновременной модуляции амплитуды и частоты в общем случае произвольного соотношения времени запаздывания отраженного излучения и периода модулирующей функции. Выполнены расчеты характеристик амплитудной селекции и их сечений, а так-же временных и спектральных диаграмм автодинных сигналов для случая модуляции амплитуды и частоты по гармоническому закону. При этом рассмотрены случаи, когда время запаздывания отраженного излучения значительно меньше продолжительности периода модуляции, а также при их соизмеримых значениях. Экспериментальные исследования выполнены с применением генератора на диоде Ганна 8-миллиметрового диапазона длин волн. Исследованы варианты электрического управления по частоте при помощи варикапа и по цепи смещения диода Ганна. Полученные результаты исследований генераторных модулей позволили сформулировать требования к параметрам и характеристикам создаваемых гибридно-интегральных схем и модулей с частотной модуляцией и наметить пути их дальнейшего совершенствования. Носков В. Я., Богатырев Е. В., Игнатков К. А., Шайдуров К. Д. Влияние сопутствующей амплитудной модуляции на формирова- ние сигналов автодинных радиолокаторов с частотной модуляцией. Ural Radio Engineering Journal. 2020;4(2):127–166. DOI: 10.15826/ urej.2020.4.2.001