The analysis of autorouter efficiency in the known CAD systems under structural and technological constraints is carried out. The revealed significant constraints are related to the thermal strength of the wires and possible mutual influence through the electromagnetic field. When manually designing the designer guided by his own experience, can ignore these and other constraints. Unlike a person, the autorouter strictly fulfills all the specified constraints, which, given the topology of the printed circuit board, does not allow tracing to complete. On the other hand, giving greater freedom to the autorouter often makes it impossible to meet the production requirements on permissible parameters of the topological pat-tern, which is the width of the conductors and the gaps between them. The problem of tracing printed circuit boards, including multilayer ones, has become much more complicated with the introduction of integrated circuits in TSOP, MOFP and BGA type enclosures packages with fine-pitch pins, a number of which can reach several hundred. The article investigates the possibility of maximizing printed circuit board topological space with these and other types of enclosures. The necessity of introducing a buffer zone around the component to improve the routing efficiency is explained. It is shown, however, that the avail-ability of a buffer zone does not eliminate the appearance of vias in it, the number of which depends on the routing type. On the basis of the proposed criterion for the autorouter performance, i.e. the ratio of the total wire length to the number of vias, the efficiency of using the topological space of a printed circuit board by three autorouters is analyzed.The presented experimental results of competing routing systems TopoR and Specctra confirmed the possibility to enlarge the pattern area of the printed circuit board for its further use.

Nowadays Vivaldi antennas are used as directional emitters with matching and balancing device at the input. As a rule, these devices cause additional losses in case of broadband operation. Besides, the use of the device leads to radiator pattern distortions, especially when operating in a wide frequency range. Stringent operating requirements (wide operating temperature, high humidity, salt fog, vibration, etc.), make the choice of proper chip very complicated. The aim of the study is to develop a slot antenna with a 50-ohm port at the input, which would be easy to manufacture and operate, while maintaining high gain in a wide frequency range. As is known, the field structure in the coplanar line is close to the field structure in the slit field close to it. As is known, the field structure in the coplanar line is similar to the field structure in the slot line. Using mathematics for such fields, means of electrodynamic modeling and numerical calculation, a system is developed that consists of two Vivaldi antennas fed by one coplanar line. Thus, the emitter has a close to a circular pattern and low losses in the structure of feeding, matching and balancing, the functions of which are performed by the coplanar line. The results are given for the frequency range of 1-6 GHz. The device as a whole is a dielectric substrate with radiating structure made as double-sided metallization. Finline-based emitters are acceptable to use for operation in higher frequencies. Antenna has low manufacturing cost and it is easy to repeat. Currently the authors are continuing work on the study of the use of such elements as part of antenna arrays.

This paper considers circular antenna arrays comprised of symmetrical dipole radiators applied in communication, navigation and monitoring systems. Despite their widespread use, a number of significant issues is underinvestigated. Among them are frequency dependence of the antenna factor (the ratio of the electric field intensity module to the voltage amplitude at the load connected to the output terminals) of the circular antenna array elements in the correct electrodynamic setting. The purpose of this paper is to analyse the antenna factor frequency dependence of a single dipole antenna with different geometry and load both in free space and as circular antenna element. The estimation of phase difference error between the circular antenna array elements caused by their cross coupling is also of interest.

Specific expressions are obtained for the antenna factor of the dipole antenna for single-mode and three-mode approximations. The limits of their applicability in frequency band are considered. The solution to the coupled integral equations is obtained using the Galerkin method with piecewise sinusoidal current distribution and with an arbitrary number of basis functions for eight- and four-element circular antenna array. This solution may be generalized to an arbitrary number of circular antenna array elements. It is demonstrated that to improve the antenna factor frequency dependence it is advisable to use dipole antennas with high-resistance load, as well as with large diameter. Phase errors for different circular antenna array element signals are considered with respect to the reference element. The dependence of these phase errors on the circular antenna array geometry is presented. It is concluded that there are significant oscillations of the antenna factor when the dipole is the part of the circular antenna array. They are caused by cross coupling between the circular antenna array elements, which significantly depend on the element spacing. The results presented may be of interest to phase direction finder development engineers.

For the VHF broadband direction finder, coherent and incoherent direction finding algorithms for switched and non-switched connection of the antenna array (AR) to receiving device in single-signal and multi-signal direction finding modes are developed and investigated.

Their synthesis is based on the methods of space-time theory of radio systems. Numerical calculation of the direction finding characteristics of the algorithms for different number of antenna array elements determines the operating range upper limiting frequency, in which this configuration provides single-value estimates of the azimuth and elevation angle. Statistical simulation modeling shows that for an odd number of antennas, the antenna array amplitudephase response is unique in a wider frequency band than for an even number of antennas. Due to this MUSIC based property applied in the space of antenna array elements, direction finding algorithm is developed for wide frequency band with several signals overlapping in frequency, with switched and non-switched AR connection to a radio receiver. It is shown that the use of ESPRIT and MUSIC methods in free-space diagram does not allow for direction finding in a wide frequency band with the antenna array fixed configuration. The results of the field studies of the developed algorithms are presented for the single-signal and multi-signal modes of operation, software and hardware implemented in the VHF radio direction finder. A comparative analysis of the developed algorithms with the known APs with fixed configuration is performed. It is shown that with the same AR configuration, it is the direction finding algorithm that determines the frequency range in which the direction finding is unique.

This paper considers an algorithm for development of the sixth order compact microstrip bandpass filters with quasi-elliptic characteristics. The proposed technique is applied for synthesis of two filters for the L- and X-band. The recursive computational approach is employed to obtain the coupling matrix with simple topological implementation. Next, the full-wave transmission line analysis based on spectral-domain method of moments is applied for calculation of coupled microstrip resonator eigen frequencies. This approach is then used to compute magnitude and sign of the coupling coefficient for basic coupled resonator configurations. Finally, two quasi-elliptic filter topologies are synthesized and structure optimization in Ansys HFSS is performed. As a result, prototypes of the developed microstrip filters are manufactured and measured.

The purpose of this research is to create new automatic methods for endoscopic image digital processing, ensuring their high ergonomics and the possibility of effective use in clinical decision support systems. As the result of investigation, the following methods were proposed: the detection and removal of specular highlights; compensation of radial and tangential geometric distortions; the mosaic panorama creation from the input video stream with low level of detail; brightness and contrast enhancement, providing simultaneous successful correction of both dark and bright areas of the image (uneven contrast) without significant underlining of the noise component typical for the existing nonlinear contrasting methods, especially in low-detail image areas; custom color correction based on linear transformation matrix taking into account endoscopic image characteristics and making it possible to customize color palette according to the physician individual preferences. The methods considered were successfully tested on real endoscopic images at the department of innovative medical devices of the Korean Electrotechnological Research Institute. The test results demonstrate their effectiveness and applicability in clinical decision support systems.

The study object is the search procedure for a ground-based radionavigation system signal using noise-like discrete signals with a long baseline. A comparative analysis of the signal search quality indicators is carried out, which is the most time-consuming procedure with different navigation signal modulation formats in the worst-case conditions and with a limited frequency resource allocated to the system.
Bandwidth efficiency of noise-like signals (NLS) with phase shift keying (PSK) and minimal frequency shift keying (MFSK) are analyzed. Relations are obtained for the average maximum search time of the navigation signal with a fixed probability of correct search completion. The qualitative indicators of the search procedure for PSK and MFSK are compared for the same band pass effectiveness and elementary symbol duration.
The analysis results show that under the conditions of equal restrictions on the occupied frequency range and the same requirements for the search procedure reliability, NLS MFSK search is effective and implementable at much lower time costs than NLS with traditional binary PSK.

Nowadays passive bistatic radars (PBR) allow for detection, determination of coordinates and tracking of moving objects. In order to enable PBR integration into air traffic control systems, it is necessary to solve the problem of recognizing airborne objects, in particular, propeller-driven aircraft (AC). This will increase the degree of aviation safety. To solve the recognition problem, the analysis of propeller-driven aircraft echo signals, such as helicopter and propeller airplane, is performed. The in-formative features that can be used for recognition of propeller-driven aircraft in PBRs are defined. The method for propeller-driven aircraft recognition is proposed, that is based on extraction of modulation components originated from the rotational parts of the aircraft and estimation of their rotation parameters. The algorithm for echo signal processing is developed, which makes it possible to apply the proposed recognition method for PBRs.
The experimental results of the processing algorithm are presented on the example of real signals reflected from the Mi- 8 helicopter and the Cessna 172 propeller aircraft. The experimental data are recorded by two different PBRs using DVB-T2 digital terrestrial television signals standard for airspace illumination. The estimated rotation parameters of the aircraft propeller blades correspond to the actual values. Such a correspondence allows not only to recognize the aircraft group, but in some cases to identify its type.

The purpose of the paper is to study the wave propagation in a two-layer pipe, taking into account the rigidity of the contact between its layers. It is considered by solving the equation of motion for the vector and scalar potentials. A dispersion equation describing the frequency distribution of the phase velocities of waves in the waveguide under investigation is derived. In order to take into account the degree of contact rigidity between layers additional terms are added to the boundary conditions, including the normal (kGN) and tangential (kGT) contact rigidity coefficients. It is shown that torsional waves are separated from other types of waves and can be considered separately. The example of a numerical solution of the dispersion equation shows the possible behavior of dispersion curves without regard to the contact rigidity. The similar problem solution is provided with allowance for contact rigidity at various perforation coefficients. A conclusion is drawn on the effect of contact between layers on torsional wave behavior. The similar method solves the problem for a homogeneous pipe with internal stratification. Recommendations are given for taking into account the revealed regularities in the development of ultrasonic methods of control based on torsional wave propagation.

The routine method to control metal surface layer is Vickers hardness test method. The existing nondestructive testing methods are based on measuring induction density and other magnetic quantities in magnetizer core. This causes the method error and restricts the ability to determine the structure of the processed material. The paper provides theoretical and experimental investigation of the method for controlling the hardened axis layer parameters by analyzing characteristics of stray magnetic field of the axis magnetized local surface area before and after rouletting. A method is proposed for determining the hardened metal layer thickness of the rolling stock axis, based on measuring the parameters of the magnetized local area stray magnetic field before and after processing. To justify the proposed method, mathematical modeling of stray magnetic field of the axis local magnetized section is performed before and after processing. Inspection for the hardened metal layer is performed using magnetization of the axis local segment with electromagnet, followed by measuring the stray magnetic field strength. The maximum value of the horizontal magnetic force is determined, which is an informative parameter. A mathematical model is developed for the magnetized section magnetic field, the results of numerical and field experiments are presented. The discrepancy between the experimental data and the results of theoretical calculations is estimated. The method makes it possible to control the thickness of the hardened metal layer and the quality of the hardening of the rolling stock axis.

This paper considers one of the challenging tasks during surgical procedure, i.e. depth of anasthesia estimate. The purpose of this paper is to investigate the effect of the analyzed EEG signal fragment duration on the accuracy of anesthesia level estimate using the linear discriminant analysis algorithm and determining the EEG signal length, which yields acceptable accuracy of anesthesia level separation using these parameters.

A new method for classifying EEG anesthesia levels is proposed. The possibility of classifying levels of anesthesia is demonstrated by means of sharing the EEG parameters under consideration (SE, BSR, SEF95, RBR).
The method can be used in anesthesia monitors that are used to monitor the depth of anesthesia in order to select the appropriate dose of anesthetic drugs during operations, thus avoiding both cases of intraoperative arousal and excessively deep anesthesia.

Electromyographic noise is one of the most common noises in electrocardiogram. In case of several electrocardiogram leads, electromyographic noise affects each lead to different extent. It can be taken into account when developing algorithms for multilead electrocardiogram record processing. However, in the existing literature, there is no information about the relationship of electromyographic noise in various ECG leads and their joint probability distribution. The purpose of this paper is to study statistical characteristics of electromyographic noise in ECG signal, from which the electromyographic noise is extracted. The paper proposes a method for extracting electromyographic noise from electrocardiogram signal, based on a polynomial approximation of electrocardiogram signal fragments in sliding window with overlapping fragment subsequent weight averaging. Using this method, fragments of electromyographic noise are extracted from multichannel electrocardiogram records. Based on the obtained data, a joint probability distribution function of electromyographic noise in two adjacent leads is selected, and the correlation relationships between the electromyographic noise in various ECG leads are investigated. The results show that the joint probability distribution function of electromyographic noise in two adjacent leads in the first approximation can be described using bivariate normal distribution. In addition, between the samples of electromyographic noise from two adjacent leads quite strong correlation relationships can be observed.