ABSTRACT. This article proposes an approach that makes it possible to provide a single bandwidth in bandpass filter (BPF) based on transmission lines (TL) segments. All another (parasitic) bandwidths except for the main are suppressed. This BPF uses two types of resonators, which are interconnected by TL segments of half-wave length. Proposed resonators are included in the BPF as parallel stubs. Some resonators are nonuniform TL resonators with a shorted end, while others are uniform TL resonators with an open end. The effect of suppressing all parasitic bandwidths is achieved by a special mutual placement of resonant and antiresonant frequencies of resonators of two types.

The traditional design, which uses couplings between resonators, is not applicable to the considered filters. Therefore, parameters of a single-band filter, which provide the required bandwidth, are determined numerically. In this way, dependences that allow calculating the filter parameters are constructed.

ABSTRACT. The problem of synthesis of stepped impedance resonators (SIRs) and resonators with stubs, which contain segments of transmission lines of the same length and suppress harmonics of the main signal, is solved. It has been established that SIR with N composite segments allows us to continuously suppress (N  1) harmonics 2f0, 3f0, ..., Nf0 of the main signal with a frequency f0. To do this, it is necessary to match the anti-resonant frequencies of the SIR with the specified harmonic frequencies. Simple expressions are established to determine the characteristic impedances of SIRs with four composed segments. It is shown that the transition from SIR to stub resonators improves their practical feasibility. Using the circuit simulator, the reliability of the presented solution was confirmed.

ABSTRACT. The problem of the stationary torsion oscillations of the opposite crack-surfaces, cracks are located in elastic biomaterial with thin interior layer, is solved by using non-classical boundary conditions. A system of two-dimensional boundary integral equations (BIEs) of the Helmholtz type with respect to unknown tangential displacements of the defects surfaces is deduced. Dependences of dynamic stress intensity factors (DSIF) in the cracks vicinity on the loading frequency and the material mismatch are analyzed.

ABSTRACT. The two-dimensional problem of scattering of horizontally polarized shear elastic waves by interphase thin inhomogeneity is solved. The inhomogeneity is located in the infinite matrix on part of the surface of the fiber with a non-canonical cross-section. The matrix, fiber and inhomogeneity are isotropic elastic bodies. The thickness of the inhomogeneity is variable, and the shape of its ends can be rounded or sharp. The problem is solved using the null field method. The spectrum of the amplitude of scattered waves in the far wave zone is analyzed for different forms of the fiber depending on the mechanical and geometric parameters of interphase inhomogeneity.

ABSTRACT. A method of studying dynamic stresses in orthotropic plates with holes has been developed. To solve the problem, the Laplace transform and the method of integral equations are used. The kernels of integral equations are given as the sum of kernels for a static problem and integrated functions. The Prudnikov formula fitted to dynamic problems of the theory of elasticity is used to perform the Laplace inversion. Dynamic stresses near an elliptical hole for various anisotropic materials are calculated. It is shown that the developed algorithm allows us to determine dynamic stresses over time with controlled accuracy.

ABSTRACT. Resonance properties of the transducers of ultrasound non-destructive testing system are investigated. Experimental system for investigating frequency characteristics of ultrasonic transducers is described. A sinusoidal model for input and output signals is used. Versions of the Prony method for frequency finding robust to noise and low-frequency interference are proposed. Several versions of the method of selective rational interpolation in the frequency domain are compared.

ABSTRACT. Using the methods of mathematical modeling, the values of the radar cross section (RCS) of the Su-27 aircraft model and trihedral corner reflectors in the high-frequency wavelength range were obtained. The scattering characteristics are estimated for trihedral corner reflectors that used as the main scattering element in the proposed model of an airborne radar decoy. The presented results show that in order to obtain sufficiently high values of the RCS of a radar decoy when probing from the front hemisphere, it is necessary to use a "quadruple" corner reflector. If it is necessary to simulate the exact median values of the RCS of a real object in a narrower range of irradiation angles, then it is better to use one tilted corner reflector. It is reasonable to use the obtained results at the developing aerial decoys to simulate the scattering of various complex aerodynamic objects, if corner reflectors are used as a reflective element.

ABSTRACT. The method of a calculation of electrical characteristics of a loop antenna with a large dimension is proposed.

ABSTRACT. This paper presents a PIFA- Planar Inverted FAntenna at 2.45GHz. The 2.45 GHz band needs a miniature Planar inverted F antenna, which is the aim of the project. ensuring that, when coupled to a 50-ohm source without an additional feeding circuit, the proposed antenna has a VSWR of less than 2 over the 2.4 GHz ISM band. The design is simulated using HFSS and also the PCB Antenna designer application in MATLAB 2021b. The proposed antenna is finally fabricated and shows a good Gain and the measured results are closely matched with simulated results and are satisfactory for the design frequency. For further evaluation, the same design is simulated using Another EM simulation tool and the results are validated.

ABSTRACT. The issue of the spatial selection possibility of radio radiation sources using a single-position phase system with the use of a range-adaptive antenna array, which allows work in a complex radio-electronic environment, is considered.

ABSTRACT. The power parameters of the short horizontal symmetrical dipole antenna, located in the immediate vicinity of a flat-layered medium composed of two lossy dielectrics are numerically analyzed. Calculations were performed in the frequency range of 1-100 MHz, which is interesting for lunar low-frequency and very low-frequency radio astronomy. The layered medium is composed of two dielectrics, parameters similar to Moon’s minerals, regolith, and granite. The frequency dependences of the impedance, the radiation efficiency, and the effective area of a thin wire dipole with a short length are investigated. All calculations were carried out by simulation of the dipole using the Altair FEKO software.

ABSTRACT. This paper proposes a monopole antenna with an ultra-wide band (UWB) for the 5G millimeter wave applications, by enhancing the circular monopole antenna's resonant structure the crescent-shaped monopole antenna is proposed. A rectangular slot was added to the ground to improve the antenna feed and extend the antenna impedance bandwidth. The antenna is supplied by a 50 microstrip line. The suggested antenna meets the -10 dB return loss bandwidth requirement from 15.4 to 40 GHz, according to simulation findings. The antenna gain is more than 3.4dBi in the 15GHz to 27.5GHz band and greater than 4dBi in the 27GHz to 40GHz range. Surface currents between the antennas cause mutual coupling in these sorts of antenna arrays, which lowers the system performance. Mutual coupling between antennas will be decreased by adopting metamaterial unit cell of spiral ring resonator.

ABSTRACT. The paper deals with the effects that accompanied the Super Typhoon Kong-Rey action in the ionosphere over the People’s Republic of China (PRC). The observations were made using the Harbin Engineering University, PRC, multifrequency multiple path coherent software defined radio system. The typhoon began on September 29, 2018 and ceased to exist on October 6, 2018. The ionospheric response to the super typhoon action was clearly observed to occur both on October 1–2, 2018 (when the typhoon was 2,800–3,300 km from the propagation path midpoints and its energy gained a maximum value) and on October 5–6, 2018 when the typhoon was 1,000–1,500 km from the midpoints and its energy decreased by a factor of about 4. The ionospheric effects are more pronounced along the nearest propagation paths, whereas no effect was detected along the propagation path at the farthest distance from the typhoon. The super typhoon action on the ionosphere was accompanied by the generation or amplification of quasi-periodic variations in the Doppler shift by a factor of 2–3, as well as by noticeable variations in the signal amplitude. The Doppler spectra were observed to broaden in a number of cases. The period of wave perturbations exhibited variability in the ~20 min to ~120 min range, which suggests that the perturbations in the ionospheric electron density were caused by atmospheric gravity waves (AGWs) generated by the typhoon; in addition, the greater the AGW period, the greater the Doppler shift. As the period increased from 20 min to 120 min, the Doppler shift amplitudes increased from ~0.1 Hz to 0.5–1 Hz. The amplitude of quasi- periodic variations in the electron density increased from a 0.4 to 6 of per cent within the same range of the AGW periods. The Doppler measurements have shown that the dusk terminator and super typhoon acted synergistically to amplify the ionospheric response to these sources of energy.

ABSTRACT. The results of observations of the motion of the ionospheric plasma over Ukraine during the partial (up to 37.8% of the Sun’s area) solar eclipse on September 1, 2016, which occurred in the magnetically conjugate region for Kharkiv (near the island of Madagascar, 37° 35 N, 47° 26 E), and during June 10, 2021 partial (4.4% in area) solar eclipse over Kharkiv (49 36 N, 36 18 E) are presented. The Kharkiv incoherent scatter radar and digital ionosondes were used for these ionospheric observations. On September 1, 2016, changes were observed in the temporal variations of the vertical component of the ionospheric plasma drift velocity, which caused by the solar eclipse in the southern hemisphere and associated with the processes of interaction through the magnetosphere between the ionospheres of the magnetically conjugate regions of the southern and northern hemispheres of the Earth. These changes were manifested in a decrease in the absolute value of the velocity of the downward motion of plasma in the ionosphere over Ukraine with an extremum 42 min after the maximum phase of the solar eclipse in the magnetically conjugate region. This effect is opposite to effect that generally caused by the solar eclipse over Kharkiv. The beginning of the velocity fluctuation coincided in time with the maximum phase of the solar eclipse, and the end was 1 h 16 min after the instant of greatest eclipse. The velocity deviation amplitude increased with altitude and amounted to 5-45 m/s at altitudes of 200-580 km. The velocity fluctuation was accompanied by a similar fluctuation in the temporal variation of the critical frequency with a maximum decrease of 0.7 MHz and in the temporal variation of ionospheric F2 peak height with a maximum increase of 30 km. The response of the ionosphere to the partial solar eclipse on June 10, 2021 with a small obscuration of the Sun (0.112 in diameter, 0.044 in area) at the studied altitudes of 180–500 km was very weak or absent at all, in contrast to results of previous observations of solar eclipses over Kharkiv with greater obscuration of the Sun's disk area (0.31 and more).

ABSTRACT. Various PSP and U-Net architectures for forest segmentation in remote sensing pictures have been proposed and investigated. The main improvements of the proposed architectures are based on using the BathNormalization layers, replacing MaxPool2D layers with AveragePooling2D, changing Conv2DTranspose to UpSampling2D blocks, etc. For the training of neural networks was used modified dataset of 128x128 pictures based on the dataset from Kaggle. As a result of improving architecture was given the maximum segmentation accuracy of 80.8 % on the validation set of pictures.

ABSTRACT. We present a concept of atmospheric gravity wave (AGW) detector based on the fuzzy logic approach. The random-generated data as well as the data acquired using Kharkiv incoherent scatter (IS) radar are employed to test the expert system under development. We designed and selected input and output variables, types of membership functions and wrote the rules for the operation of the expert system. As input variables, we used two equivalent signal-to-noise ratios and oscillation durations at two adjacent heights as well as differences between phases, onsets and periods of these oscillations. Detection capability and belonging to wave were assigned to the output variables. Testing of the program detector using a number of randomly generated signals showed that it correctly detects the received signal the determines the signatures of wave patterns. We also apply the developed approach to detect traveling ionospheric disturbances caused by AGW propagation near local solar terminator passage times in the altitude-time maps of IS power.

ABSTRACT. The contribution of specialists of Pivdenne State Design Office, Joint Stock Company “Khartron”, and “Pivdenmach” to the creation of spacecraft for remote sensing of the Earth in Ukraine in the 1970s – 2020s was studied. The key stages of the creation of space vehicles, which were developed by specialists of the “Pivdenne”, such as Ocean-OESC, Ocean-O1SC, Ocean-OSC, Duga-K SC, Bhaskara SC, Bhaskara-IISC, Egyptsat-1SC, Sich-1SC, Sich-1MSC, MikronSC, Sich-2SC, Sich-2-30SC were illustrated. The work performance of remote sensing spacecraft is characterized. The contribution of specialists of branch enterprises of the State Space Agency of Ukraine to the creation of a space operational system for the study of natural resources of the Earth “Resurs”, and the development of a method of remote measurement of physical parameters of the ocean and atmosphere, calibration of remote sensing data, as well as a system of over-the-horizon radar, and space means of radio-electronic surveillance was outlined. It is shown that the participation of scientists in the solving of many scientific and technical problems like the creation of space vehicles for obtaining information simultaneously in the optical, infrared, and microwave ranges contributed to the further development, and to the creation of innovative methods, and technical means of remote sensing; to the solving practical and scientific tasks in the study of the atmosphere, and the World Ocean; and the implementation of the Ukrainian and international space programs such as Sich, Interkosmos, Ocean, and Egyptsat-1.

ABSTRACT. The European community recognises advanced materials as key to providing solutions to many industrial and societal challenges, including the green and digital transition [1]. Accurate and reliable characterisation methodologies and computational modelling are needed to accelerate the development of new materials and to reduce the cost and time-to-market for new products [2]. These issues have given rise to many R&D projects under the European Framework Programmes. To coordinate and guide the associated research efforts dedicated entities have been established such as the European Materials Modelling Council (EMMC), European Materials Characterisation Council (EMCC), and Advanced Materials 2030 Initiative (AMI2030). The above challenges have long been known in microwave engineering and become specifically acute in the emerging 5G / millimetre-wave technologies, where complex and miniaturised designs require ultra-low-loss dielectric substrates and metallic traces. Material properties need to be precisely known in order to optimise 5G hardware performance and assure its quality. The Speaker will first present her team's experience in R&D projects on both the European (H2020, M-ERA.NET) and global (iNEMI [3][4]) scale in the field of assessment of material testing methods for microwave and millimetre-wave applications. Benchmarking results will be interpreted with the help of full-wave computer simulations with QuiickWaveTM software. Synergies between computer modelling and experimental characterisation of materials, as explored by QWED, will be discussed. The second part of the talk will elaborate on the European initiatives such as EMMC, EMCC, and AMI2030, their offers and needs for broader international collaborations.

1] “MATERIALS 2030 MANIFESTO. Systemic Approach of Advanced Materials for Prosperity. A 2030 Perspective”, 7 Feb. 2022; https://www.ami2030.eu/wp-content/uploads/2022/06/advanced-materials-2030-manifesto-Published-on-7-Feb-2022.pdf [2] N. Adamovic, B. Boskovic, M Celuch, C. Charitidis, J. Friis, G. Goldbeck, A. Hashibon, E. Hurtós, M. Sebastiani, and A. Simperler, ”Advanced materials modelling and characterisation: strategies for integration and interoperability”, Report from EuroNanoForum2021 Satellite Event, 4 May 2021; https://zenodo.org/record/4912683#.Y2gsdXbMLdM . [3] The International Electronics Manufacturing Initiative. https://www.inemi.org/in%20progress [4] M. Celuch, M. J. Hill, T. Karpisz, M. Olszewska-Placha, S. Phommakesone, U. Ray, and B. Salski “Benchmarking of GHz resonator techniques for the characterisation of 5G / mmWave materials”, Proc. 2021 51st European Microwave Conference (EuMC), London, April 2022; DOI: 10.23919/EuMC50147.2022.9784292 [5] N. Adamovic, G. Goldbeck, and M. Celuch, "MODA and CHADA; challenges and opportunities for integration and exploitation to industrial stakeholders beyond EU projects", NanoMECommons Co-Creation Workshop on "Materials characterization challenges to support the industry transition in the digital era", 24 Nov.2022; https://www.qwed.eu/nanobat/EMMC_MODA_CHADA_NanoMECOmmons_CoCreation_WS.pdf

ABSTRACT. In this work the resonant frequencies in spheroidal metallic cavities loaded with isotropic and anisotropic material, are studied. For the case of isotropic infills, an extended boundary condition integral equation method (referred hereafter as extended integral equation) is employed while, a local point technique is developed for anisotropic loadings. The anisotropy used in this work is of uniaxial type while prolate and oblate spheroidal cavities are studied. The extended integral equation is based on numerical integration of the involved special functions along the generating curve of the spheroidal surface. On the contrary, the local point technique satisfies the requisite boundary condition at a predefined set of points on the generating curve without the necessity to apply integration techniques. The emerging hybrid modes are examined and discussed. In particular, the spheroidal cavity spectrum for isotropic infills is extracted and compared by both the extended integral equation and the local point technique. Concerning uniaxial loaded cavities, the resonant frequencies are calculated solely by the local point technique. To validate these results, we utilize the HFSS commercial software. The local point technique turns out to be computationally efficient in terms of CPU time and memory consumption, as compared to the commercial solver. Various numerical results are presented and discussed.

ABSTRACT. In spite of the centennial age of radar, this technology is facing continuous progress. This overview paper considers two significant items in this field, namely Noise Radar Technology (NRT) and Quantum Radar (QR). Status, ongoing research and future perspectives are briefly discussed, not forgetting some critical and controversial elements.

ABSTRACT. The results of simulation of the main electrodynamic characteristic of a controllable disk microstrip antenna are presented. A distinctive design feature is the presence of semicircular grooves in the microstrip disk and controlled semiconductor diodes. The grooves had different radii and were located symmetrically about the vertical axis of symmetry at angles of 450. The antenna was fed using a segment of an unshielded coplanar line. Diodes with the help of auxiliary segments of microstrip conductors had galvanic contact with grounded elements of the coplanar line. The simulation was performed within the framework of the Finite Element Method (FEM) and its software implementation using the ANSYS HFSS package. It has been established that by optimizing the parameters of the grooves, it is possible to achieve an acceptable level of matching in a relatively wide frequency band. Possibilities of control of pattern characteristics at change of state of semiconductor diodes are shown.

ABSTRACT. The paper presents the results of modeling the main electrodynamic characteristics of a disk microstrip antenna with a set of slotted inhomogeneities. The geometric dimensions of inhomogeneities meet the law of decreasing geometric progression with a given denominator. Antenna feeding is carried out using a complex composition element: connection with external circuits is carried out using a segment of a grounded coplanar line, and the excitation of the disk resonator itself is carried out using an additional ring resonator. The simulation was carried out within the framework of the finite element method. The possibility of operation in several frequency subranges is shown.

ABSTRACT. The results of the study of the MARK-4B antenna system of RT-32 radio telescope functional capabilities in S- and X-band are presented. It has been determined the frequency bands for effective antenna system operation. A theoretical and experimental study of the corrugated feed horn operation possibilities in the S- and X-band has been carried out. The radiation pattern of the antenna system was measured using the Cygnus A radio source in two frequency subranges of the X-band. It is shown that the antenna system can work effectively in the found frequency subranges of S- and X-band. Some promising options for design of a waveguide system for separating S-/X-band signals with orthogonal polarizations are presented

ABSTRACT. In this study, we developed and investigated a flexible LTE antenna for a wearable IoT device. This flexible antenna is double-sided, has geometric dimensions of 40.0×12.0 mm and is placed inside a rubber wristband of the device worn on arm. The upper surface of the antenna is radiating, and the lower surface of the flexible antenna is shielding. The antenna has weak directional properties to reduce the energy of electromagnetic radiation in the direction of a human body. When the antenna is placed on a person's arm, its operating frequency range is 787.88 MHz - 863.64 MHz and 1717.84 MHz - 1880.352 MHz.

ABSTRACT. The paper deals with electromagnetic problem of the radiation generated due to the excitation of a periodic interface of an artificial material with dispersive constitutive parameters by an electron beam moving over this interface. It is demonstrated that the possibility of excitation of eigen waves of periodic surface has the principal influence on the radiation characteristics, which show anomalously high levels of the secondary filed. It is also shown that an accurate solution to the spectral problem, allowing numerical modeling of eigen regimes, provides the profound description and physical explanation of the complicated electromagnetic phenomenon.

ABSTRACT. We study the resonant transmission of normally incident plane electromagnetic wave through the metasurface consisting of two overlapping one-periodic bar gratings with mechanically tunable crossing angle in free space. The bars of the gratings are made of PEC-like material of nonzero thickness. It was theoretically revealed and experimentally confirmed that the frequency of the sharp lattice resonance depends on the crossing angle and shifts towards higher frequencies if the crossing angle increases. It was shown theoretically that the lattice resonances split if the overlapping one-periodic bar gratings have different periods. Near field patterns above and below the structure were obtained at the frequencies of the resonance peaks.

ABSTRACT. Finite one-dimensional magnetophotonic crystal containing magnetized plasma layers is considered in Voigt configuration. Combined theoretical method based on the Floquet-Bloch waves method and transfer matrix one is used for obtained analytical expressions for dispersion relations, transmission and reflection coefficients. Pronounced nonreciprocal properties of the magnetophotonic crystal are shown for oblique incidence of wave on the structure. Transmission coefficients are different for opposite signs of incidence angle. Nonreciprocity is observed within the transmission band of surface gyrotropic waves within subbands between Fabry-Perot resonances.

ABSTRACT. During the optimization by means of genetic algorithms of the three-dimensional rod arrays consisting of finite-length cylinders, commonly used in the design of high-frequency resonance scattering, three-dimensional solvers, such as the multilevel fast multipole algorithm, perform the analyses with a time bottleneck. Simulation results seem independent of longitudinal dimensions in many applications. Therefore, the exploitation of the well-conditioned solvers in two dimensions appears to be worthy, and it is aimed to cast further comparisons between the two types of solvers in this contribution.

ABSTRACT. The perfectly electrically conducting cylinder of arbitrary cross section is illuminated by a plane wave with no electric/magnetic field component along the longitudinal direction obliquely impinging onto the obstacle with a non-zero angle from its surface normal. The electric and magnetic field integral equations modeling the phenomenon are elaborated. The super algebraically convergent algorithms are exploited for calculation of their kernels. Magnetic field integral equations lead to well-conditioned corresponding algebraic systems naturally while electric field integral equations lead to well-conditioned corresponding algebraic systems after their Analytical Regularization which will be outlined, where beforehand they are ill-conditioned. Solutions of both equations verify each other. After post processing these solutions, the accuracy as well as the condition of the algebraic systems will be investigated for each equation having incidence angle as a parameter.

ABSTRACT. Basis functions localized in all spatial coordinates (so-called partial functions or oscillets) are suggested for expansion of non-stationary non-harmonic electromagnetic potentials in dispersive electrodynamic systems (ESs). Those are defined as linear transformations of the ES eigenfunction manifold minimizing the practically significant spatial spread of the oscillets. It is advisable to use new functions in electrodynamic computations and optimizations of irregular ESs of microwave sources including lengthy and open-ended (having a continuous spectrum of eigenfunctions) ones. An example of usefulness of the partial functions application for simulation of a longitudinally inhomogeneous ES is given.

ABSTRACT. In this article magnetron model has been developed for explanation why the electron beam had wavelike form before oscilation stage. As well known in crossed-field devices electrons move by cycloid-like trajectories. In accordance with the diocotron effect electron beam form was wavelike form because interaction between RF wave and electron beam. But at preoscillation stage we had the same electron beam form in magnetron both planar and cylindrical. Such form we explained by space periodical distribution of an electrostatic potential distribution.

ABSTRACT. Some aspects of calculating the characteristics of corrugated cavities for second-harmonic gyrotrons are considered. The influence of spatial Fourier harmonics supported by corrugations on cavity eigenfields is studied. In some specific cases, a comparison of the Bloch harmonics method with the spatial harmonics method for low and high radial modes is presented. It is shown that the method of spatial harmonics, as opposed to Bloch harmonics method, provides accurate data on eigenfield distribution along the cross-section of the corrugated waveguide, with the exception of small areas near the edges of the corrugations.

ABSTRACT. A fast theoretical approach is extended to take into account mode conversion induced by an azimuthal slot in a complex gyrotron cavity excited by a helical electron beam. As an example, a modified complex cavity with intermediate slot for a second-harmonic 0.4-THz gyrotron is considered. For this gyrotron, the influence of the slot on starting current of the operating mode and output mode purity of the complex cavity is investigated. The obtained results are found to be in contrast to what might be expected from the cold-cavity calculations. The reason is related to the effect of the electron beam on formation of the combined operating mode of the complex-cavity gyrotron.

ABSTRACT. The research and development of thermionic cathodes for the clinotron tubes operating in millimeter and THz ranges resulted in fabrication of several types of electron emitters based on oxide cathode technology, L-cathode and dispenser cathode. Presented consideration of both advantages and disadvantages of these cathodes allows to optimize the electron optical system of the clinotron tubes of different frequency bands taking into account the requirements for the starting current, output power, radiation spectra etc. The development and application of the dispenser cathode, which emitter part consists of fine spherical powder composed of pure tungsten phase with favorable dispersity, allowed us to obtain the beam current density higher than 50A/cm2 in the compact diode electron gun in the static magnetic field and to form the intense sheet electron beam with the current up to 200mA at the accelerating voltage up to 6kV.

ABSTRACT. The operation of the THz Cherenkov vacuum electron devices with nonuniform double gratings supporting the hybrid bulk-surface modes has been considered for an increase of a thickness of a sheet electron beam and its coupling with RF field. It is shown that advantages of a double grating configuration may comprise the increase of up to 3 times of a coupling impedance as well as a widening of the operation frequency range in comparison with the single grating configuration.

ABSTRACT. The study of the emission properties of the 140 GHz corrugated horn antenna in the frequency range 170-174 GHz has been presented and discussed. This extended frequency range is a part of upgrade of the collective Thomson scattering (CTS) diagnostic at Wendelstein 7-X stellarator. The antenna characterization was done using the raster scan method and thermographic measurements with the help of 175 GHz Clinotron oscillator. The experimental results showed the possibility of the antenna application for the new CTS detector in the both frequency ranges at 140 GHz and 174 GHz.

ABSTRACT. The features of an experimental study of the effect of precipitation, such as, water, snow, ice and their mixture on the surface of cm-wave meteorological radar antennas on signal parameters because of decreasing the gain are shown. Also the results of synchronous measurements of the reflector antenna gain, rain intensity and amount of precipitation on the reflector are presented. It is shown that the presence of even a small amount of moisture leads to a significant decreasing the gain. This is especially important for meteorological radars at measuring the absolute values of the power of signals reflected from meteorological objects.

ABSTRACT. A millimeter-wave horn antenna with an external dielectric lens is considered. It has been experimentally shown that the rotation of the lens around an axis perpendicular to the longitudinal axis of the antenna system leads to an increase in the signal level at the antenna receiver. A simplified two-dimensional model of the system is developed on the base of FDTD method implemented in the MEEP package. The simulation results indicate a change in the axial focusing of the lens when it is rotated. It has been established that the main physical mechanism that causes an increase in the signal level at the antenna receiver is resonant phenomena in the volume of a dielectric lens. These phenomena are similar to the well-known half-wave resonances in a plane-parallel plate with oblique incidence of a plane wave.

ABSTRACT. The paper concerns the analysis of the antenna system adjustment peculiarities. The method of checking the reflectors optical characteristics and their layout, as well as estimating the system capabilities composed of specific nodes are considered. The development of the methods and approaches to modeling process of large satellite antennas adjustment, assessing of their electrical parameters and finding the element's location that will provide the necessary AS parameters is described. The practical implementation results of the authors' approaches to the AS ERS adjustment process are given.

ABSTRACT. In this work, a tunable dual-band filter has been designed. Triangular Half-Mode Substrate Integrated Waveguide (HMSIW) resonators have been used to miniaturize the filter to get a smaller device footprint. A dual-band filter operating at 9 GHz and 14 GHz first and second pass-band center frequency is built using Rogers-5880 substrate with a permittivity of 2.2. To reconfigure the center frequencies of the first and second pass-bands, dielectric rods have been used to perturb the structure. The diameter of the dielectric rods are varied from 0.2 mm to 0.8 mm, and the center frequency for the first pass-band changed from 8.1 GHz to 9.15 GHz, while the center frequency of the second pass-band changed from 14.61 GHz to 16.10 GHz. The dielectric rods' permittivity was also changed to alter the structure's overall permittivity and a frequency change from 8.1 GHz to 9.1 GHz and 14.61 GHz to 14.74 GHz has been observed for the first and second pass-band, respectively.

ABSTRACT. A method of design of a broadband septum polarizer with a square common port is proposed. It is based on a classical configuration with a longitudinal stepped metal insert. The results of numerical optimization of its profile showed that it makes no sense to use more than four steps in the single-mode regime, since an increase in their number does not lead to an improvement in the characteristics of the device. It is shown that this limitation is absent in the multimode mode, and it is possible to achieve better device characteristics by increasing the number of steps. The design of a broadband septum polarizer with a bandwidth of 40% in the multimode regime is presented.

ABSTRACT. A case study of Two-Dimensional Imaging of the Cessna-172 aircraft is presented. This imaging technique is widely employed by Inverse Synthetic Aperture Radars (ISAR) to improve the radar performance and provide it with some radar vision options. The study features experimental records of the airplane's wideband radar returns. The case study employs a straightforward approach using the time-frequency distributions to obtained focused ISAR images. The approach that employs the Choi-Williams distribution is used together with traditional Fourier analysis. The records of wideband radar returns pertaining to a variety of aircraft were obtained at Chungnam University, Republic of Korea, before 2006 during an elaborate field experiment. A file with wideband radar returns from the Cessna-172 aircraft was recorded and transferred to the authors of this article under Contract #06-45-3/179-D between the Chungnam University, Republic of Korea, and the Kharkiv University of Radioelectronics in 2006.

ABSTRACT. The paper describes the principles for formation of a simulated pulse DRFM jamming in response to a sounding linear frequency modulated (LFM) pulse, the technique and results of mathematical (simulation) modeling of such a jamming.

ABSTRACT. Image lossy compression is currently widely employed in different fields. Compared to lossless compression, it allows providing a considerably larger compression ratio but distortions are introduced inevitably. Properties of these distortions depend on a used coder, an image subject to compression, and compression parameters. Distortions affect visual perception of compressed images and efficiency of their further processing. Thus, statistical and spatial spectral properties of introduced distortions have to be understood well to explain effects observed in compressed image processing and, possibly, enabling their simulation. In this paper, we describe the tools that can be used in analysis of distortion properties and give an example of such analysis for grayscale images compressed by AGU coder. It is shown that distortions, in general, have spatially variant statistics where they are more intensive in locally active areas. Besides, distortions are spatially uncorrelated for all considered quantization steps and, respectively, compression ratios. Experiments are carried out using four typical remote sensing images.

ABSTRACT. The papers presents a data acquisition hardware and software that have been designed for 16-th antenna Stepped-Frequency Noise SAR with MISO configuration for 2D real-time imaging. Data acquisition board, program algorithm and its realization are described. There is considered a multi thread program realization and program execution time estimation. Experimental results of 2D real-time image processing are presented.

ABSTRACT. An expansion of the use of UAV images requires the improvement of methods and means for image analysis and processing in order to effectively solve various problems. Visual quality metrics play a key role in this sense, since their use allows determining the need in different image processing operations, their type and parameters, automating the entire process. The paper considers the problem of using no-reference visual quality metrics and test image databases to solve such problems. The effectiveness of more than 40 existing visual quality metrics for images with typical distortions for UAVs has been evaluated. The paper proposes a combined metric based on an artificial neural network to improve the accuracy of visual quality assessment and the possibility of its application in practice with sufficient efficiency

ABSTRACT. The mechanism of detection of sea surface height and wind speed using pulsed radar is elucidated. Associated methods and test equipment were developed. A comparative experiment is carried out, and some conclusions with practical application value are drawn by controlling the equipment parameters of the pulse radar. Partial differential and polar transformations were applied to extract the RCS features of the sea surface.

ABSTRACT. In the presented work, based on the representation of the total flow of range request signals, as well as intentional correlated and uncorrelated interference to a range-finding radio beacon as a Poisson flow, the capacity of both the range-finding beacon range transponder and the short-range radio engineering system as a whole is estimated based on the implementation of the method for extracting synchronous sequences of incoming range interrogation signals in the ground range transponder. It allows on a succession basis to move from the service signal to a requester service and, as a result, increase the throughput of the long -range radio beacon in question.

ABSTRACT. Using the example of a waveguide metacell, it is shown that the introduction of additional rings of slots into a bilayer planar-chiral iris in a circular waveguide generates new resonances of the artificial optical activity (AOA). Their origin is the excitation of new eigenoscillations inside the bilayer gap and the corresponding rotation of the polarization plane at the output of the meta-object. Even with slight chirality of the layers, these rings increase the number of AOA resonances in the single-mode band. In loci of proximity and transformation of eigenoscillations inherent in planar-chiral bilayers, AOA maxima are observed with a rotation of the polarization plane up to 90°, and an expansion of the AOA band up to 10% can be achieved.

ABSTRACT. Aperture eigenoscillations of a plane junction of a circular waveguide with a set of rectangular waveguides have been studied. They play a decisive role in generation of eigenoscillations of more complex waveguide components, which include considered plane junctions. It is shown that the real part of the frequency of an eigenoscillation can be reduced by increasing the number of rectangular waveguides arranged in compliance with rotational symmetry and/or their widths. The eigenoscillation can be shifted below cutoff of the circular waveguide in the case of two wide rectangular waveguides. It is shown that when rectangular waveguides are arranged along concentric rings, the number of eigenoscillations increases with an increase in the number of rings.

ABSTRACT. We propose simple and efficient way to control the propagation regime and direction of spoof surface plasmon-polaritons localized at bilayer hyperbolic metasurfaces. We demonstrate the photonic topological transition at the same frequency implemented with a mutual rotation of the metasurface layers. Finally, we show the tunable multidirectional in-plane canalization of surface waves adjusting by the interlayer coupling. These results discover new opportunities for the manipulation over surface waves at metasurfaces.

ABSTRACT. In this work, we study the surface electromagnetic waves propagating along the self-complementary metasurface. We propose a way to excite the surface waves of the necessary polarization by using the TE-TM degeneracy property of the self-complementary metasurface. In particular, we demonstrate the excitation of surface waves with linear horizontal, vertical and diagonal as well as circular polarizations. The proposed technique opens new possibilities for the in-plane signal transferring and transformation.

ABSTRACT. The paper presents the results of the investigation of oscillations in 1 μm-length InN Gunn diode with a graded GaInN layer are assessed by means of hydrodynamic simulation. A graded GaInN – InN layer is used to stimulate the generation of a drifting electrical domain in an InN diode. The oscillations were investigated at different mole fraction of Ga in graded GaInN alloy, different length of graded GaInN layer and different electron density in an active region. The average oscillation power, the oscillation frequency and the direct current power of the diode operation both with and without a resonator are presented in paper. The characteristics of different diodes are compared. InN diode with a graded GaN - InN layer has the highest oscillation power and the smallest direct current power and InN diode has the highest oscillation frequency are obtained. The maximum oscillation frequency is 419.7 GHz

ABSTRACT. The paper presents results of a new set of numerical simulations, plus first experimental data concerning excitation of lasting VHF oscillations by an electromagnetic shock which travels through a coaxial guiding structure. The structure is characterized by radial nonuniformity of its filling material and a nonlinear electrodynamic response of the gyrotropic fraction of that (ferrite). The physical effect underlying the excitation is the Cherenkov-type speed synchronism between the driver (the shock wave) and the wave mode existing in the ferrite medium.

ABSTRACT. The work substantiates the possibility of increasing the efficiency of lasers by smoothly expanding the radiation beam in the active substance. This makes it possible to use the energy of the active substance as efficiently as possible, avoiding the effect of saturation. A scheme of a laser resonator using the principle of smooth expansion of the radiation beam in the active substance is proposed. Recommendations are developed for the practical application of the proposed scheme and its variations in lasers of various ranges.

ABSTRACT. We present a surface electromagnetic eigenmode of a plane separating the negative permeability metamaterial and vacuum. The wavefields decreased exponentially out of the interface between the media. This wave is of TE-polarization with an electric field paralleling the interface. Mode is a fast wave because its phase velocity is more than the speed of light. Besides, the mode is a backward wave since the phase and group velocities have opposite directions. Such fast surface electromagnetic waves can be used for designing modern so-called “fast-waves devices” for both wave generation and amplification.