# Orest VendikPetersburg State Electrotechnical University · Radiophysics

Orest Vendik

Doctor of Engineering

## About

249

Publications

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3,692

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Introduction

Additional affiliations

January 1989 - February 2016

## Publications

Publications (249)

Electromagnetic (EM) wave propagation inside and along the surface of the human body is the subject of active research in the field of biomedical applications of microwaves. This research area is the basis for wireless monitoring of biological object parameters and characteristics. Solutions to the following problems are crucial for achieving the s...

The development of microwave power amplifiers (PAs) based on transistors with an AlGaN/GaN heterojunction are discussed in terms of the possible enhancement of their efficiency. The main focus is on the synthesis of the transforming circuits, which ensure the reactive load at the second- and third-harmonic frequencies and complex impedance at the f...

Biological medium surrounding an implanted device is characterized by a high dielectric permittivity and a loss factor. This fact results in a degradation of the electromagnetic signal by a strong wave reflection from the interface and refraction phenomena accompanied by the total internal reflection at the interface between the biological tissue a...

The results of modeling and an experimental study of electromagnetic (EM) waves in microwave range propagating along the surface of the human body have been presented. The parameters of wave propagation, such as the attenuation and phase velocity, have also been investigated. The calculation of the propagation of EM waves by the numerical method FD...

A technique for synthesis of microwave power amplifiers based on transistors with a AlGaN/GaN heterojunction is discussed. Special focus is on the development of a technique for synthesis of transformation circuits of the power amplifier to increase efficiency with a retained high output power. The use of independent matching at the harmonic freque...

In this paper, an original design of a low-profile loop antenna with increased directivity is proposed. Odd- and even-mode currents excitation in the loop allows providing two times higher gain than the gain of a single loop or dipole. The special design of a power dividing network in order to excite odd- and even-mode currents with the amplitude e...

The paper focuses on modeling and experimental investigations of electromagnetic waves propagating over the surface of a human body. Wave propagation parameters such as attenuation and phase velocity are of main interest. The results of analytical and numerical simulations are compared with measured data.

In this paper, an original design of a low-profile loop antenna with increased directivity is proposed. Odd- and even-mode currents excitation in the loop allows providing two times higher gain than the gain of a single loop or dipole. The special design of a power dividing network in order to excite odd-and even-mode currents with the amplitude eq...

The structural properties of ferroelectric barium strontium titanate films deposited at different temperatures and electrical parameters of related tunable capacitors were investigated before and after an annealing in oxygen atmosphere at different temperatures. It has been shown that both deposition and annealing temperature directly affect the ph...

Radio-frequency identification systems used for the remote diagnostics of diseases and contactless monitoring and assessment of human health are reviewed. The propagation of electromagnetic waves inside a biological medium and along interfaces between different media, as well as the problem of telemetry data acquisition from implanted systems or sy...

A novel method for the estimation of the mutual coupling between radiators in antenna arrays is presented in this article. The methodology proposed includes the analysis of the radiation pattern of the single radiator in the antenna array. An algorithm based on the calculation of real and imaginary parts of the antenna mutual impedance using the Kr...

A calculation procedure is proposed to design the p-i-n diode phase shifter based on the waveguide transmission line. The laboratory sample of five-bit phase shifter designed using the proposed procedure was fabricated and measured at 32–36 GHz. It provides the following phase shifts bits: 11°, 22°, 45°, 90°, 180°. © 2015 Wiley Periodicals, Inc. Mi...

Issues pertaining to modeling of the propagation of electromagnetic waves in a biological medium are considered, including the wave refraction at the biological medium-free space interface. The behavior of the complex dielectric permittivity as a function of the frequency is analytically described. Power losses related to the reflection of waves pr...

The electromagnetic properties of electrically small loop antennas for two different applications are discussed: near-filed and far-field RFID systems. In the first case miniature loop antennas are designed for the near field wireless biological and medical sensing application. The magnetic field in the near-field zone is used for coupling between...

A novel method for the calculation of the mutual coupling between radiators in antenna arrays is presented. The proposed methodology includes the analysis of the radiation pattern of a single radiator. An algorithm based on the calculation of real and imaginary parts of the antenna mutual impedance using the Poynting's Theorem and the Kramers - Kro...

A novel high-Q resonant structure comprising the bulk acoustic resonator (BAR) and inductive loop is proposed to be used for wireless power transmission system. The proposed resonant structure operating at MHz frequency range has significantly miniature size in relation to the electrical wavelength (<λ/100) that could be attractive in the field of...

Amplitude-phase distribution of currents in the emitters that allows
independent control of the main lobe and the blind spot on the
directivity pattern of the antenna where the gain substantially
decreases is analyzed. The problem is solved with the aid of controlled
amplitudes and phases of the waves emitted by the antenna array. The
main lobe and...

Microwave microstrip resonators and filters controlled by ferroelectric
capacitors have been simulated and experimentally studied. Control at
room temperature and under cryogenic conditions has been ensured by
capacitors based on BSTO and STO films, respectively. Cooled devices
based on YBa2Cu3O7-δ
high-temperature superconducting films have been f...

In the above-named article [ibid., vol. 2, no. 5, pp. 538-555, Sep. 2012], the authors would like to correct the following print error in the legend to Fig. 14, which should be read as follows: "Fig. 14. Broad-band active metamaterial in the THz region [69]. (a) Schematics for resonator patterns on a VO2 thin film and a SEM image. (b) SEM image. (c...

A metamaterial is a composite material that has attracted the attention of researchers since the late
1990s–early 2000s. This material contains an artificial periodic structure, which modifies its permittivity and
permeability and, thereby, makes it possible to control the dispersion, refraction, and reflection of electro�
magnetic waves in the met...

Two synthesis procedures of an adaptive antenna array based on the amplitude-phase and only-phase perturbations for providing reduction of susceptibility of jamming are presented. The jamming suppression is achieved by the side lobe cancellation in a required direction. We consider a receiving antenna, which is characterized by the direction of the...

Phased antenna array synthesis procedures based on the amplitude-phase and only-phase distributions providing the side lobe cancellation in a required direction are presented. A receiving antenna array was considered. It is characterized by the direction of the main beam for receiving the useful signal and the additional nulling direction. The requ...

A procedure of synthesis of an adaptive antenna array providing reduction of susceptibility to jamming or interference is presented. This approach is based on the sidelobe cancellation in the required direction. In this case, the form of the radiation pattern can be transformed by a modification of the system of sampling coefficients. An example of...

A structure of an electrically large loop antenna segmented by planar two-ware capacitors is considered. An analytical model for calculating input impedance of this antenna type is proposed.

Polymer coatings on the basis of the biphenol-Novolac potting epoxy compound with a 65% content of spherical particles of fused quartz as a filler were studied by the method of dielectric spectroscopy in a wide frequency range. Dielectric measurements were performed in frequency and temperature ranges of (10−2 to 5 × 109) Hz and 20 to 200°C, respec...

Complex approach to the design of microstrip resonators and filters based on High Temperature Superconductor (HTS) films is described, which includes modeling of the electrodynamics parameters of HTS films, design of microstrip resonators and filters, their manufacturing, and testing. Test samples of resonators were prepared using YBCO films on LaA...

We consider a microwave phase shifter based on thin-film ferroelectric parallel-plate capacitors operating as a part of a phased array at an elevated microwave power level and for a limited power in the control circuits. To eliminate capacitance modulation in parallel-plate capacitors by an ac field, we propose the separation of the effects of the...

The characteristics of fourth-order bandpass microwave filters based on high-temperature super-conductor (HTS) films have
been numerically simulated and experimentally measured for the devices based on YBCO films purchased from Theva GmbH (Munich)
and manufactured at the Institute for Physics of Microstructures (Nizhni Novgorod). Experimental data...

The common features in dielectric and m echanical characteristics of the Epoxy Molding Compound (EMC) were found in temperature dependencies of the dielectric permittivity and the dielectric loss factor obtained in experiments by Electro-Dynamic Analysis (EDA) in comparison with the temperature dependence of storage modulus and mechanical loss fact...

The work of Alexander Popov, who was professor of physics and for a short period the director of the Electrical Engineering Institute, now called Saint Petersburg Electrotechnical University, is described. He studied X-rays, constructing an X-ray tube and displaying the X-ray phenomenon before an open audience just after Roentgen's discovery in 189...

The structure of a loop antenna of electrically large diameter with the loop perimeter split by capacitors in the form of
planar two-wire (PTW) lines is considered. The antenna characteristics are calculated for one- and two-sided arrangement of
the PTW lines and the obtained data are compared to the results of measurements. It is shown that the ar...

Complex approach to the investigation of microstrip resonators and filters based on High-Temperature Superconductor (HTS)
films is described, which includes modeling of the electrodynamic parameters of HTS films, designing of microstrip resonators
and filters, their manufacturing, and testing. Test samples were prepared using YBCO films on 0.5-mm-t...

New requirements are formulated for phase shifters used in phased-array antennas: 1) small power in biasing networks, 2) higher microwave power, 3) low production cost. Reflection type phase shifters on ferroelectric tunable capacitors in combination with hybrid junction form a transmission type phase shifter. Two ferroelectric capacitors are conne...

A metamaterial that is formed by two types of spherical particles of different diameters has been considered. The particles
are prepared from a ferroelectric ceramic material with a high permittivity (ɛ ≥ 400), so that the electromagnetic field inside
the particles obeys the electrodynamic laws and the external field can be considered in the electr...

Rapid progress made in the physics of ferroelectrics is accompanied by the appearance of new requirements for the design of
microwave phase shifters that serve as base elements in phased-array antennas, which, apart from traditional applications
in radiolocation, have been widely used in various telecommunication systems. Nowadays, microwave phase...

A model describing the dielectric properties of a composite material with ellipsoidal ferroelectric inclusions has been developed. The dependence of the effective permittivity of the composite material on the applied external electric field is determined for different sizes of ferroelectric inclusions. The controllability of the composite material...

In April of 2008, Dr. Jacob Baal-Schem invited me to serve as a member of the panel discussion on the subject of "Who invented Radio", which had to be held in the USA during IEEE Communications Society Globecom 2008. At that time, a few questions were put me concerning activity of Professor A.S. Popov. Unfortunately I could not participate in the G...

Two approaches to modeling the size effect in a ferroelectric parallel plate capacitor are considered: (i) spatial correlation of polarization under the influence of boundary conditions on electrodes of the capacitor and (ii) “dead layer” model. For the description of the spatial correlation, the Landau–Ginzburg–Devonshire equation is used. The cha...

In this paper we discuss a potential realizability of a tunable bulk acoustic filter based on BSTO film for microwave applications. The estimation of characteristics of the tunable TFBAR was done by processing the experimental data obtained for the BSTO resonator using the model of the induced piezoelectric effect. The third-order tunable TFBAR fil...

The combination of a dipole and a tunable varactor forms a phase shifter with one tunable component that provides a phase shift over a wide range, from 0deg to nearly 360deg. The dipole, loaded with a tunable varactor, is used as a patch component of a low-profile reflectarray antenna. An economic assessment shows that the production price of the s...

Design of a novel planar antenna, which is based on a combination of a dipole and a loop that provides a cardioid radiation pattern in two planes and therefore a hemispherical coverage, is proposed. The dipole-loop antenna with hemispherical radiation pattern and doubled gain as compared with conventional omni-directional antennas could be promisin...

The effective dielectric permittivity of a nanostructured ferroelectric film consisting of elliptic ferroelectric grains has been theoretically studied as a function of the grain size and the thickness of a dead (nonferroelectric) surface layer in inhomogeneous grains.

A model for tunable thin film bulk acoustic resonators (TFBARs) based on ferroelectric films is proposed. The model is based on electromechanical equations taking into account piezoelectric effect and electrostriction effect induced by the dc electric field. The dc field induced shift of the resonant frequency is explained by the high-order nonline...

Isotropic sample of single ferroelectric crystal (STO) with cubic symmetry or the epitaxial BSTO film does not exhibit a piezoelectric effect, but is characterized by electrostriction. The induced piezoelectric effect occurs under the dc electric field. Using electromechanical equations for this material in presence of both the dc and ac electric f...

A reliable model of a tuneable bulk acoustic resonator based on BSTO film with induced piezoelectric effect is proposed. The estimation of resonance and antiresonance frequency shift of bulk acoustic resonator as a function of the applied voltage has been carried out. The results of the input impedance modelling of the BSTO bulk acoustic resonator...

The dependence of the effective dielectric permittivity of a nanostructured ferroelectric film on the grain size and the thickness of a dead (nonferroelectric) surface layer in inhomogeneous grains has been theoretically studied.

A tunable capacitor based on a ferroelectric thin film grown on a dielectric substrate is a promising component for reconfigurable and tunable devices for numerous RF and microwave applications such as phase shifters, tunable filters, and tunable matching networks. The goal of this paper is characterization of the insertion loss in a reflection-typ...

A composite medium consisting of two sublattices of dielectric spherical particles of high permittivity and different radii embedded in a dielectric matrix of smaller permittivity are considered. It has been shown that such a composite medium reveals properties of an isotropic double negative media in the frequency range where resonance oscillation...

A composite medium consisting of two sublattices of dielectric spherical particles of high permittivity and different radii
embedded in a dielectric matrix of smaller permittivity are considered. It has been shown that such a composite medium reveals
properties of an isotropic double negative media (DNG) in a limited frequency range, when resonance...

A novel approach to design digital phase shifters with the operational bandwidth extended to one octave is presented. An original design of the broadband phase shifter based on switching between transmission lines (TLs) with positive and negative dispersions is considered. An artificial TL with the negative dispersion was implemented as a quasilump...

An artificial dielectric medium comprising two sublattices of spherical particles made of a high-dielectric-constant (high-ε)
material, which are embedded into a low-ε dielectric matrix, are considered. Particles belonging to different sublattices
have different diameters. It is shown that the properties of this composite structure are equivalent t...

An analytical model for a SQUID amplifier with double Josephson junctions is proposed, with an equivalent scheme representing
a long transmission line loaded on the junctions via a mutual inductance that varies along the line. The results of analytical
calculations agree with the results of numerical simulations. An analysis shows that load matchin...

Novel phase shifter structures have been suggested, simulated, and designed. The phase shifters are based on a connection of transmission line sections with positive and negative dispersion. Use of a combination of such sections allows designing miniature microwave devices operating in a wide frequency range. Different phase shifter structures are...

The propagation of electric and magnetic fields and of the Poynting vector in the near zone (Fresnel zone) of an electric
dipole, a loop, and a dipole-loop pair is considered. The dimensions of all radiators are much smaller than the radiation
wavelength. It is shown that the ideas of the field distribution (polar diagram) in the far zone cannot be...

Compact miniature microwave phase shifters have been designed on a combination of conventional (righthanded) transmission line sections and dual ones (left-handed) with negative dispersion. The phase shifters of two kinds are under consideration in this paper: an analog tuneable phase shifter using ferroelectric varactors as the tuneable components...

Planar capacitors, consisting of a thin ( ≈ 1 μm) ferroelectric film and a dielectric substrate, widely used at microwaves, are normally designed on the basis of the conformal mapping technique and the use of the traditional formula for electric field in the capacitor gap: E = U/s. U is applied voltage and s is the width of the gap. The important c...

Microwave application of ferroelectrics is very promising for electrically tunable microwave devices based on the electric field dependence of the dielectric permittivity. Tunable filters and controllable phase shifters are successfully designed as integrated circuits based on multilayer structures containing thin epitaxial ferroelectric (FE) film....

The properties of a multicoupled microstrip line (MSL) with a thin control ferroelectric layer have been analyzed in terms
of a full-wave model based on the method of moments in spectral domain. The Q values for all fundamental modes and their contributions to MSL losses are determined. It is established that various fundamental
modes in multicoupl...

Original design of a broadband digital phase shifter based on switching between transmission lines with positive and negative dispersion is presented. A simple approach to design phase shifters with the operational bandwidth, which can be extended to one octave regarding both the phase shift and the input matching, is considered. Artificial transmi...

The periodic composite medium consisting of two lattices of different dielectric spherical particles has been investigated analytically and numerically. It is shown that effective isotropic double negative media (DNG) can be realized in the frequency region where resonance of TM mode in one kind of particles and TE mode in another kind of particles...

It is ascertained that the size effect in thin ferroelectric films is related to the spatial correlation of ferroelectric
polarization, depending on boundary conditions. The influence of the size effect on the permittivity of displacive ferroelectrics
is described. It is shown that the size effect manifests itself differently for different orientat...

The aim of investigations of barium-strontium titanate solid solution Ba<sub>x</sub>Sr<sub>1-x</sub>TiO<sub>3</sub> BSTO films and ceramic layers is a realization of tunable components for microwave tunable filters and microwave tunable phase shifters for steerable antenna arrays. The experiment with a tunable resonator on a strontium titanate (STO...

The use of thin film layered electrodes allows the unloaded Q-factor of a resonator to be enhanced due to resonant transmission of microwave power through metal sublayers. Use of superconducting films as the conductor plates needs additional analysis to establish the validity of applying the multilayer electrode consideration in this case. The meth...

The review of the published data (1991-2003) for MMIC phase shifters is performed. For the analysis of the characteristics of the considered phase shifters the universal parameter (figure of merit) is introduced and used to compare the phase shifter characteristics based on different switching elements.

Different tunable microstrip resonators are suggested to be used in tunable microwave filters. Ferroelectric capacitors are chosen as the tunable components of the resonators. A novel criterion for description of the performance of the tunable filters is suggested.

A new design approach for a microstrip tunable filter on a two-layered substrate with BSTO thin films is suggested. The coupling factor of a ferroelectric capacitor connected to the microstrip resonators of the filter is considered to make possible the design of the filter with constant pass band width while tuning. Results of the filter characteri...

The goal of this paper is estimation of an achievable figure of merit of microwave phase shifters. The microwave dissipation in ferroelectric material, conducting electrodes of ferroelectric components and the loss in an external circuitry are taken into account. Equations for a theoretical estimation of an achievable value of the phase shifter fig...

The ways to solve a problem of providing stable operation of microwave ferroelectric phase shifters for steerable antennas in a wide temperature range are briefly considered. A ferroelectric phase shifter based on cascaded tunable ferroelectric planar capacitors is properly described. The connection of the tunable capacitors in series with transmis...

A method for calculating the capacitance-voltage (C-U) characteristic of a planar ferroelectric film capacitor with allowance for the material nonlinearity is proposed. The nonlinear properties of the ferroelectric material are described in terms of the Ginzburg-Devonshir equation under the conditions of minimum free energy of the planar capacitor....

The microwave losses in electrodes of a ferroelectric-based transmission line and a lumped ferroelectric-based element have
been theoretically analyzed. The results of calculations of the effective loss tangent for the transmission line are confirmed
by a two-dimensional electrodynamic model analysis and by experiments with a coplanar phase shifter...

A correct and verifiable model of the dielectric loss factor of BaxSr1−xTiO3 as a function of temperature, biasing field, barium concentration, and frequency has been developed in frequency range 0.1–100 GHz. Contributions to the loss factor of fundamental, quasi-Debye, acoustic, and low frequency relaxation mechanisms have been modeled. The specif...

The loss factor (tan delta) of ferroelectric material at microwaves and the tunability (n) defined as a ratio of the dielectric permittivity at zero dc field to the dielectric permittivity at the given field are strongly connected with the softness of so-called ferroelectric soft mode. The loss factor and the tunability are generalized by the commu...

The properties of a microstrip line (MSL) on a bilayered substrate containing a thin ferroelectric layer are theoretically
studied. The propagation parameters are calculated using an approach based on a two-dimensional full-wave electrodynamic model.
The influence of the fringing electric field in the ferroelectric layer on the MSL characteristics...

By incorporating a variable position short circuit plunger in one of the side arms, a magic-T can be used to separate the variations in the resistive and reactive parts of a load impedance. The technique is particularly well suited for measuring transient variations of the impedance, and this paper deals with the variation of impedance of a 25 μm w...

A microwave method was used for investigating the change of the impedance of a thin copper wire which takes place due to a short current pulse with a density of 4 × 106 A cm-2. The excitation of the longitudinal oscillation in the wire and delay in change of its resistivity with respect to time of the current pulse were obtained.

An overview of microwave activities and infrastructures in Europe
is presented. The material is organized in 17 sections, each devoted to
a country or group of countries and prepared by an. internationally
renowned microwave expert. In general, each section contains some
history of microwaves in the region, and highlights some microwave
activities...

A method for the determination of the noise spectral density in a high-temperature microwave SQUID operating in the hysteresis
regime is developed. Under these conditions, the reflection coefficient serves as an output signal. It is shown that if a
directional coupler used for extracting the reflected wave is placed as close to the SQUID loop as po...

An experimental investigation of high-temperature dc SQUID amplifier connected in series with a high-Tc superconductor (HTS) thin-film band-pass filter is presented. The SQUID amplifiers are designed with microstrip input coils and fabricated on bicrystal substrates of zirconia and sapphire with different misorientation angles of 24� and 37�. SQUID...

The temperature dependence of a capacitance of a planar capacitor based on Ba <sub>1-x</sub> Sr <sub>1-x</sub> TiO <sub> 3 </sub> (BSTO) films was investigated and some anomalies were observed. It was experimentally found that the barium concentration decreased across the film thickness in the direction from film/substrate interface to the film sur...

Commercial applications of ferroelectrics at microwaves can be realized in a case of mass production of field effect phase shifters (FEPS), aimed to be element of electronically steerable antennas (ESA). Such phase shifters are designed as microwave integrated circuits based on ferroelectric films. In order to provide a high reproducibility of FEPS...

A novel microstrip tunable filter design approach is suggested. Coupling factor of a ferroelectric capacitor connected with the microstrip resonators of the filter is considered to make possible the design of the filter keeping constant the pass band width while tuning. Results of the filter characteristic simulation and measurement are presented.

The commutation quality factor (CQF) is suggested as a generalized criterion of the material tunability and its loss factor. The figure of merit of a switchable device is uniquely determined by the CQF. From this point of view the CQF is used as a working tool for optimization of the microwave devices. A comparison between analog and digital ferroe...

The range of a tunability of the filter with ferroelectric capacitor is determined by the commutation quality factor (CQF), which takes into account both the tunability of the capacitor under biasing voltage and the loss factor. For effective tuning, the CQF should be high enough (more than 1000). The main goal of the tunable filter synthesis is to...

The most promising microwave ferroelecric device is a ferroelectric phase shifter, aimed to be an element of a phased-array antenna. The following characteristics of the phase shifter are important: microwave insertion loss, range of operational temperatures, life time. Designing microwave tunable components is based on carefully developed models o...

Novel design of an integrated digital reflection-type phase shifter based on a Barium Strontium Titanate thin-film capacitor is presented. Measured characteristics of the phase shifter are compared with the theoretically predicted ones.

A procedure of extracting model parametrs of a ferroelectric thin film from the experimental characteristics of the capacitance and the loss tangent of a planar capacitor is proposed. It is based on a correct phenomenological model of the capacitance and the loss tangent of the planar capacitor containing the ferroelectric thin film. The calculatio...

A reflection type phase shifter based on a tunable ferroelectric capacitor is under consideration. A design and characteristics of the one-bit ferroelectric phase shifter is proposed and discussed. The minimal insertion loss of the phase shifter is limited by the commutation quality factor of the capacitor and can be achieved in the case when the l...

The use of high temperature superconductor (HTS) films provides a higher selectivity of planar filters. The lower out-of-band interference increases the sensitivity of receiving systems and allows reduction of transmitter radiated power. Our goal was to show how these filters can be designed with a desired accuracy, and to give evidence for a real...