Dmitry S. Kozlov
Queen's University Belfast
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Publication
Featured researches published by Dmitry S. Kozlov.
IEEE Transactions on Terahertz Science and Technology | 2012
Irina Vendik; Orest Vendik; Mikhail Odit; Dmitry Kholodnyak; Svetlana P. Zubko; Margarita F. Sitnikova; Pavel Turalchuk; Kirill Zemlyakov; Irina Munina; Dmitry S. Kozlov; Viacheslav Turgaliev; Alexey B. Ustinov; Yeonsang Park; Jinyun Kihm; Chang-won Lee
Remarkable progress in terahertz (THz) sources and detectors is followed by the necessity of manipulating of terahertz radiation. Since natural materials can not perform efficient interaction with THz radiation, artificial structures called metamaterials are designed to overcome “THz gap” in this area. A variety of tunable metamaterials using different methods of control are presented and discussed in this review paper.
IEEE Antennas and Wireless Propagation Letters | 2012
Orest G. Vendik; Dmitry S. Kozlov
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 the forming of the required radiation pattern and corresponding current distribution is demonstrated .
IEEE Transactions on Microwave Theory and Techniques | 2016
Dmitry S. Kozlov; Alexey Shitvov; Alexander Schuchinsky; Michael B. Steer
Passive intermodulation (PIM) often limits the performance of communication systems with analog and digitally modulated signals and especially of systems supporting multiple carriers. Since the origins of the apparently multiple physical sources of nonlinearity causing PIM are not fully understood, the behavioral models are frequently used to describe the process of PIM generation. In this paper, a polynomial model of memoryless nonlinearity is deduced from PIM measurements of a microstrip line with distributed nonlinearity with two-tone CW signals. The analytical model of nonlinearity is incorporated in Keysight Technologys ADS simulator to evaluate the metrics of signal fidelity in the receive band for analog and digitally modulated signals. PIM-induced distortion and cross-band interference with modulated signals are compared with those with two-tone CW signals. It is shown that conventional metrics can be applied to quantify the effect of distributed nonlinearities on signal fidelity. It is found that the two-tone CW test provides a worst-case estimate of cross-band interference for two-carrier modulated signals, whereas, with a three-carrier signal, PIM interference in the receive band is noticeably overestimated. The simulated constellation diagrams for QPSK signals demonstrate that PIM interference exhibits the distinctive signatures of correlated distortion and this indicates that there are opportunities for mitigating PIM interference and that PIM interference cannot be treated as noise. One of the interesting results is that PIM distortion on a transmission line results in asymmetrical regrowth of output PIM interference for modulated signals.
IEEE Antennas and Propagation Magazine | 2015
Orest G. Vendik; Dmitry S. Kozlov
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 Kramers-Kronig relations is demonstrated. The validation is performed by comparing the calculated estimations with electromagnetic simulations of the antenna system and wellknown theoretical results evaluated by the method of induced electromagnetic force. The developed procedure is universal and can be applied to different types of antenna systems.
loughborough antennas and propagation conference | 2014
Dmitry S. Kozlov; Alexey Shitvov; Alexander Schuchinsky
A novel approach to the modelling of passive intermodulation (PIM) generation in passive components with distributed weak nonlinearities is outlined. Based upon the formalism of X-parameters, it provides a unified framework for co-design of antenna beamforming networks, filters, combiners, phase shifters and other passive and active devices containing nonlinearities at RF front-end. The effects of discontinuities and complex circuit layouts can be efficiently evaluated with the aid of the equivalent networks of the canonical nonlinear elements. The main concepts are illustrated by examples of numerical simulations of PIM generation in the transmission lines and comparison with the measurement results.
Progress in Electromagnetics Research Letters | 2014
Vladimir N. Yashchenko; Dmitry S. Kozlov; Irina Vendik
Original resonant structures for improving efficiency of wireless charging system with the possibility of data exchange are presented. Characteristics of two different dual-mode spiral resonators were obtained by electromagnetic and circuit simulations. Based on these results, an optimum design for highly efficient data and energy transfer was suggested.
workshop on integrated nonlinear microwave and millimetre wave circuits | 2015
Dmitry S. Kozlov; Alexey Shitvov; Alexander Schuchinsky
This paper presents initial results of evaluating suitability of the conventional two-tone CW passive intermodulation (PIM) test for characterization of modulated signal distortion by passive nonlinearities in base station antennas and RF front-end. A comprehensive analysis of analog and digitally modulated waveforms in the transmission lines with weak distributed nonlinearity has been performed using the harmonic balance analysis and X-parameters in Advanced Design System (ADS) simulator. The nonlinear distortion metrics used in the conventional two-tone CW PIM test have been compared with the respective spectral metrics applied to the modulated waveforms, such as adjacent channel power ratio (ACPR) and error vector magnitude (EVM). It is shown that the results of two-tone CW PIM tests are consistent with the metrics used for assessment of signal integrity of both analog and digitally modulated waveforms.
2017 Integrated Nonlinear Microwave and Millimetre-wave Circuits Workshop (INMMiC) | 2017
Alexey Shitvov; Dmitry S. Kozlov
This paper presents an RF CAD assisted approach to accurate characterisation of microstrip nonlinearities in planar microwave circuits fabricated on commercial printed circuit board laminates. The proposed methodology is employed for the analysis of the nonlinear effects in microstrip filters due to weak intrinsic distributed nonlinearity. The results of this study provide useful insights on the optimum design, modelling and characterisation of planar microwave components under linearity constraints.
loughborough antennas and propagation conference | 2014
Dmitry S. Kozlov; Orest Vendik
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 Poyntings Theorem and the Kramers - Kronig relations is demonstrated. Validation is performed by comparing calculated estimations to electromagnetic simulations of the antenna system and well-known theoretical results evaluated by the method of induced electromagnetic force. This procedure is universal and can be applied to different types of antenna systems.
european conference on antennas and propagation | 2015
Dmitry S. Kozlov; Alexey Shitvov; Alexander Schuchinsky