Introduction. Modern systems for active vehicle safety are designed to significantly reduce the number of road accidents. Sensors based on monocular cameras are increasingly being introduced by the world's leading automakers as an effective tool for improving traffic safety. Modern methods of localisation and classification, combined with semantic segmentation algorithms, allow for image division into independent groups of pixels corresponding to each object. However, the problem of developing segmentation algorithms ensuring improved quality of image segmentation remains to be solved.

Aim. To develop an automatic method for segmenting a given object during image analysis.

Materials and methods. An automatic method for segmenting vehicles in an image was proposed. The method presented herein allows semantic segmentation of the object of interest, based upon a priori information about the bounding boxes, which frame the objects in the image. Bounding box information is used to transform an image into a polar coordinate system where the pixels of the image act as the edges of a weighted graph. A closed contour is obtained around the object of interest by using the shortest path search algorithm and inverse transformation to the Cartesian coordinate system.

Results. The experiments confirmed the correctness of the selected area of interest based on this algorithm. Jacquard’s similarity coefficient for the Carvana open database is 85 %. Furthermore, the proposed method was applied to different classes of images from the Pascal VOC database, thus demonstrating the ability to segment objects of other classes.

Conclusion. The main contribution of the proposed method was as follows: 1) segmentation of the object of interest at the level of modern methods, and in some cases in excess thereof; 2) the study presents a new look at the way of tracking object contours.

Introduction. Increased data rate in modern communication systems can be achieved by raising the operational frequency to millimeter wave range where wide transmission bands are available. In millimeter wave communication systems, the passive components of the antenna feeding system, which are based on hollow metal waveguides, and active elements of the radiofrequency circuit, which have an interface constructed on planar printed circuit boards (PCB) are interconnected using waveguide-to-microstrip transition.

Aim. To design and investigate a high-performance wideband and low loss waveguide-to-microstrip transition dedicated to the 60 GHz frequency range applications that can provide effective transmission of signals between the active components of the radiofrequency circuit and the passive components of the antenna feeding system

Materials and methods. Full-wave electromagnetic simulations in the CST Microwave Studio software were used to estimate the impact of the substrate material and metal foil on the characteristics of printed structures and to calculate the waveguide-to-microstrip transition characteristics. The results were confirmed via experimental investigation of fabricated wideband transition samples using a vector network analyzer

Results. The probe-type transition consist of a PCB fixed between a standard WR-15 waveguide and a back-short with a simple structure and the same cross-section. The proposed transition also includes two through-holes on the PCB in the center of the transition area on either side of the probe. A significant part of the lossy PCB dielectric is removed from that area, thus providing wideband and low-loss performance of the transition without any additional matching elements. The design of the transition was adapted for implementation on the PCBs made of two popular dielectric materials RO4350B and RT/Duroid 5880. The results of full-wave simulation and experimental investigation of the designed waveguide to microstrip transition are presented. The transmission bandwidth for reflection coefficient S11 < –10 dB is in excess of 50…70 GHz. The measured insertion loss for a single transition is 0.4 and 0.7 dB relatively for transitions based on RO4350B and RT/Duroid 5880.

Conclusion. The proposed method of insertion loss reduction in the waveguide-to-microstrip transition provides effective operation due to reduction of the dielectric substrate portion in the transition region for various high-frequency PCB materials. The designed waveguide-to -microstrip transition can be considered as an effective solution for interconnection between the waveguide and microstrip elements of the various millimeter-wave devices dedicated for the 60 GHz frequency range applications.

Introduction. As a result of the extensive development of broadband communication in the millimetre wave band, there has arisen a need for antenna systems with a high level of directivity and compact dimensions, capable of operating across wide frequency ranges. However, at present, few engineering solutions satisfy this demand.

Aim. To develop and study experimentally a K-band antenna array (AR) characterized by a high aperture efficiency and compact longitudinal dimensions.

Materials and methods. Computer simulations were performed using the CST Studio Suite software. Measurements were carried out using an Agilent E8363B PNA vector circuit analyzer. Radiation patterns were obtained by the method of near-field scanning.

Results. A K-band broadband antenna array configuration operating over the 18…26 GHz range was pro-posed. It was found that the period of the array equals 2.25 wavelengths at the highest operating frequency. In order to suppress grating lobes, an additional layer consisting of artificial inhomogeneous dielectric lenses was used. The dielectric material consisted of thin curly layers of sheet polyethylene terephthalate. Additionally, a hybrid configuration of feeding network was proposed, in which one part of the network was developed by means of printed two-wire lines, while the other part was achieved by means of rectangular waveguides. The proposed antenna array demonstrates VSWR of less than 2 and an aperture efficiency above 0.5, side and diffractive lobe levels not exceed –12 in the 18…26 GHz range. The total thickness of the configuration equals 50 mm or 4.3λ_min. In order to ensure the compactness of the AR for wideband frequency applications, the thickness of the system can be reduced to 2.5λ_min by excluding the waveguide part.

Conclusion. When compared with existing solutions, the proposed antenna has a simpler feed network, which yields better matching. High aperture efficiency is achieved in the wide frequency range by means of inhomogeneous dielectric lenses.

Introduction. The resolution of the problem of radio polarimetry in multiposition microwave screening systems (MMSS) with aperture synthesis requires the use of antennas with a high level of cross-polarization discrimination (XPD) in a wide spatial angle. The radio images are reconstructed in MMSS at distances commensurate with the aperture of the antenna structures. Therefore, the value of the spatial angle, at which high XPD is required, can reach 30°. This leads to a new problem of creating an antenna configuration of the X and Ku band, the application of which in MMSS will resolve the problem of constructing a radio image of depolarized microwave radiation scattered on the human body in the form of hidden dangerous objects.

Aim. To develop a double-ridged receiving antenna for long-term operation in MMSS with an XPD level of 28 dB at a spatial angle of 30° and operating frequencies of 8…20 GHz.

Materials and methods. The requirements for the receiving antenna in MMSS were determined. Theoretical justifications were proposed for the choice of antenna design. Aperture synthesis was used to construct microwave images in MMSS. The stages and results of modelling broadband double-ridge antennas were presented using the CST Studio software broadly applied for three-dimensional electro-magnetic field modelling. The results of modelling pyramidal and conical double-ridged antennas, as well as those in circular and elliptical waveguides, were analyzed. The designed antenna was tested in an anechoic chamber. The measurement results were compared with those obtained during simulation.

Results. An elliptical double-ridged horn antenna with a VSWR of no more than 2 and cross-polarization discrimination in a spatial angle of 30° of no less than 28 dB for the frequency range that covers an octave was designed and constructed.

Conclusion. The developed antenna can be used in MMSS for the purpose of detecting the effect of micro-wave radiation depolarization as hidden dangerous objects on a human body. Such characteristics of the antenna as its high XPD value in a wide spatial angle will allow the future introduction of microwave polarimetry in MMSS.

Introduction. The current need to obtain relevant, complete and reliable information about airborne objects has led to the continuous improvement of modern radar recognition systems (MRRS) as part of control systems. The development of modern MRRS has created objective prerequisites for the use of progressive and new methods and algorithms for the processing of signals using neural networks. The use of artificial neural networks with learning ability permits expansion to include many signs of recognition by using information obtained in the process of monitoring airspace.

Aim. To formulate the problem and develop proposals for the use of posterior information for airspace control in radar recognition systems using neural network technologies.

Materials and methods. Based on an analysis of the structure of a unified information network, an approach was formulated to facilitate the development of MRRS based on training technologies. Using the synthesis method, examples of technical solutions were proposed, which will allow the use of modern methods and signal processing algorithms using a posteriori information generated by the control system.

Results. The study identified the principles of neural network training in solving the recognition problem in the process of functioning of radio electronic equipment (REE). The technical solutions pro-posed take the functioning of the integrated radar system into account, allowing the information parameters required for training MRRS in a single information field to be obtained. It is shown that the removal of restrictions associated with the functional autonomy of REE, allows the use of posterior information in the implementation of radar recognition systems. This also allows for an increase in the number of recognition signs used in the algorithms and for the database of portraits to be replenished.

Conclusion. MRRS can be developed via training by removing the restrictions associated with the autonomous functioning of RES. This allows for the situational assessment to be enhanced and management decisions to be optimised.

Introduction. The primary functions of secondary processing of radar information are to detect and maintain the trajectories of air targets (AT). The AT trajectory detection can be characterised by the probability of detecting trajectory and average autocapture time. When the target moves, its distance from the radar station changes, leading to a change in the signal/noise ratio and the probability of detecting AT.

Aim. To assess the impact of a change in the probability of detection of a straight and evenly moving target at consecutive time intervals of radar observation upon the characteristics of trajectory detection during secondary processing of radar information.

Methods and materials. The research aim was achieved using the methods of mathematical statistics, including verification of statistical hypotheses, assessment of distribution parameters and theory of perturbations by small parameters. The ratio of the distance travelled by the AT during the review period to the target range at the initial moment of its detection was chosen as a perturbation parameter.

Results. Analytical expressions were established for the probability of detecting a straight-moving AT and the probability of detecting the trajectory of its movement at interval multiples during the study period. The study illustrated the probability of detecting AT moving away from radar by means of consistent radar observations with reduced signal/noise ratios and angles between the velocity vector and the AT vector radius relative to the radar. The increase in AT speed which causes the z parameter to change from 0.01 to 0.07 reduces the probability of AT detection from 0.727 to 0.52 and leads to a corresponding change in the probability of detecting the trajectory. If the observation time is reduced by one time interval, the probability of detecting the trajectory is from 0.03 to 0.04…0.07 for signal/noise 40 ratio and from 0.06 to 0.08…0.11 for signal/noise 25 ratio (with the probability of false alarm 10–4 ).

Conclusion. The resulting expressions allow for the calculation of directly moving AT trajectory detection, considering changes in the probability of detecting targets in successive time intervals of radar observations.

Introduction. Modern air targets, particularly drones, are becoming less noticeable, while their manoeuvrability continues to improve. Trajectory processing algorithms have also been improved in order to provide for effective tracking of highly manoeuvring targets. The accuracy of filtering trajectory parameters is largely determined by the reliability of radar information. This has also required an enhanced role for strobe algorithms and the need to increase the effectiveness of strobe radar marks.

Aim. To develop and investigate the efficiency of a trajectory strobe algorithm based on the target motion model in a high-speed coordinate system associated with the direction of the target motion and involving the formation of a strobe in the form of a truncated elliptical sector.

Materials and methods. The study considered the target motion model in the body-fixed frame. This model was taken as the basis for new trajectory filtering algorithms based on Kalman filtering. Existing methods for strobing radar marks of the target were considered and a new approach based on filtering in the body-fixed frame proposed. The new algorithm assumes the formation of a strobe in the form of a truncated elliptical sector. This form corresponds to the most probable location of the marks of the tracked target. The effectiveness of the proposed solutions is confirmed by the results of mathematical modelling carried out using MATLAB.

Results. The study produced analytical expressions for the motion model, recurrent filtering and strobe algorithm in the body-fixed frame. A comparative analysis of tracking effectiveness with the same volumes of the elliptical and proposed strobes was performed. It was established that the algorithm with strobe formation in the shape of a truncated elliptical sector provides for longer target tracking up to the time of the first loss of the mark for speed and highly manoeuvring targets, when compared to the elliptical strobe algorithm. In addition, the average duration of sector strobe tracking does not in practice depend on the initial speed of the target and provides greater accuracy for small measurement error values (less than 50 m) of the coordinates than in comparison with the elliptical one.

Conclusion. The described results were achieved by the ability of the strobe in the body-fixed frame to adapt to the direction of motion and target manoeuvring, allowing high-quality target tracking within a larger speed range. Such strobe formation will also reduce the likelihood of skip-ping radar marks from the tracked target and will reduce the number of false marks belonging to other trajectories inside the strobe.

Introduction. In recent decades, in the field of photoelectronics, special attention has been paid to the development of semiconductor matrix photodetectors. These detectors have become an effective alternative to existing television receiving systems. Among such devices, linear position-sensitive sensors are used in cases where the rapid registration of changes to the environment is required (for instance, high-speed locators for flying vehicles).

Aim. To develop a strip of silicon pin-diodes as part of a hybrid IR-detector for effective registration of photoelectrons with time resolution less than 10 ns, as well as to model the key electro-physical characteristics of the strip.

Materials and methods. In the device under development, the registration of photoelectrons is achieved by the presence of a near-surface field using p ++–p junction formed by diffusion of boron into the silicon with resistivity of 3 kΩ · cm. The pulling field is also formed in the space charge region between p ++ - and n ++ -regions. Diffusion of phosphorus was carried out to create the n ++ -region. Numerical calculations of potential distribution, concentration of free charge carriers and currents were carried out using software for 1D- and 2D-modelling (SimWin and TCAD Synopsys).

Results. 2D-calculation of charge carrier concentration and potential distribution was performed. The study determined the minimum bias for the complete depletion of the i-layer, including that for longitudinal grooves of various depths. The strip was tested as part of a hybrid photoelectric device by irradiating light pulses from IR LED. When the voltage on the diodes was reached –270 V, the duration of the signal front on all channels was 5…9 ns.

Conclusion. For use in IR-hybrid detectors, a strip of 12 silicon pin-diodes was developed with a sensitive element of 24 × 0.2 mm in dimension. The study of pulse characteristics showed that the necessary duration of the front signal on all channels was achieved without thinning thus satisfying the requirements for high-speed position-sensitive sensor of the infrared radiation.

Introduction. Metal oxide semiconductor sensors have many advantages. But their working temperature is still high and their sensitivities are frequently low. In the current work, I present the results from investigation of sensing ability of new kind of potentiometric solid state gas sensor.

Aim. The main goal of this work is investigation of the temperature dependence in the flow of air and in ethanol vapour mixture of the investigated junction structures. Also, we investigated at fixed temperature the dependence of the thermoelectric force from the ethanol vapour concentration at possible low operation temperature. For the structure, which shows the lowest operation temperature to ethanol vapour, we investigate the ability to detect Pseudomonas putida suspension.

Materials and methods. In this work, the sensitivity to ethanol vapour and Pseudomonas putida suspension were investigated by measuring the thermoelectric force (the voltage) appearing of the structures by standart voltmeters.

Results. Two experimental installations for sensors have been developed. The first one is for detection of ethanol vapour by ZnO/ZnO:Cu, ZnO/ZnO:CuO, ZnO/ZnO:Fe junction structures. The second installation was for Pseudomonas putida suspension detection in gas phase by ZnO/ZnO:Fe junction structure. We discovered that ZnO/ZnO:Fe structure, has the lowest operation temperature of 200 °C to ethanol vapour. For this structure, the potential difference has a negative value and decreases with increasing the amount of the pulverized bacteria.

Conclusion. We discovered that ZnO/ZnO:Fe structure, has the lowest operation temperature of 200 °C. This operation temperature is a bit higher than operation temperature of at which some very novel sensing structures shows the maximum sensitivity.

Introduction. In-line analysis of ethanol content in gasoline blends is currently one of the urgent needs of fuel industry. Developing safe and secure approaches is critical for real applications. A phononic crystal sensor have been introduced as an innovative approach to high performance gasoline sensing. Distinguishing feature of proposed sensor is the absence of any electrical contact with analysed gasoline blend, which allows the use of sensors directly in pipelines without the risk of explosion in an emergency.

Aim. Investigation of the possibilities of using phononic sensor structures to determine the ethanol content in liquid hydrocarbons.

Materials and methods. A theoretical analysis of sensor structure was carried out on the basis of numerical simulation using COMSOL Multiphysics software. For measurement, substances of ordinary gasoline and gasoline 63–80 with ethanol concentrations in the range of 1–10 % by volume in increments of 2 % were prepared. The phononic crystal sensor was designed as a stainless steel plate with cylindrical holes and a resonant cavity, formed as a running across the wave propagation path slit between two lattices.

Results. In-line analysis of measuring the concentration of ethanol in alcohol-containing fuels on a phononic crystal structure with a resonant cavity was carried out. Using the Agilent4395A admittance meter, the transmission spectra of longitudinal acoustic waves through the gasoline-filled sensor structure with were obtained. The non-linear correlation between the composition and the speed of sound of the blend is presented in the article is due to the ability to reduce the speed of sound of the mixture with an increase in ethanol concentration in the range of 0–10 % by volume.

Conclusion. A measurement structure on the basis of phononic crystal was created. The measurements of various gasoline-ethanol mixtures show that the sensor has significant sensitivity (0.91 kHz/ms−1 ) with quality factor of 200) to distinguish between regular fuels, gasoline based blends and the presence of additives in standard fuels. The sensor has prospects for in-line analyzes the composition of liquid hydrocarbons.

Introduction. Diagnostic systems are designed to monitor the condition of operational components (for example, on the railway). It is imperative that micro-electromechanical systems (MEMS) equipped with acceleration sensors (accelerometers) be used as part of measuring diagnostic systems. It is known that accelerometers are operated under increased vibration and repeated shock loads. This imposes a limitation both on the accelerometer design and the properties of materials from which these devices are produced.

Aim. To develop a micromechanical accelerometer (MMA) for surface acoustic waves (SAW), capable of measuring shock effects.

Materials and methods. The theoretical part of the study was carried out using the mathematical theory of differential equations, theoretical mechanics, finite element analysis and elements of SAW theory. In the course of the work, the following methods of mathematical processing were applied: MATLAB, Mathcad, Maple, COMSOL Multiphysics, OOFELIE: Multiphysics, Bluehill3 software, CorelDRAW. Experimental studies were also conducted using the INSTRON 5985 floor automated test system.

Results. An original design of MMA on a SAW capable of measuring shock effects in hundreds of g was proposed. A sensing element (SE) of the sensor was developed. An analysis of the plate materials for their use as part of the SAW-based MMA design showed that SE from the quartz ST-cut material has a wider range of measured accelerations and a higher sensitivity threshold than SE from the YX-128˚ cut-off lithium niobate material. Requirements were developed to increase the SE sensitivity threshold. Design requirements were developed, and an interdigital transducer (IDT) topology in the form of a ring resonator was proposed. The following output characteristics were assessed: sensitivity threshold, dynamic range and scale factor. In addition, a procedure was developed for calculating MMA on a SAW with a ring resonator on an anisotropic material. It was found that the developed SE is characterized by a high sensitivity threshold, a wide dynamic range and a low transverse sensitivity.

Conclusion. The technique proposed for designing a sensing element for use in solid-state linear acceleration sensors facilitates, depending on technical requirements, selection of construction materials and sensor design. Due to the originality of the design and engineering solutions, the proposed accelerometer allows measurements to be carried out across a wide range of impact loads.