Browsing by Author "Okoniewski, Michal M."
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Item Open Access An Active-Loaded Phase-Conjugating Rotman Lens for Intelligent Transportation System Backscattering Applications(2018-12-10) Keshavarzian, Pouyan; Okoniewski, Michal M.; Nielsen, Jorgen; Fear, Elise C.; Belostotski, Leonid; Knight, A. M.Retro-directive backscattering is useful for improving link-budget in communication systems, localization and radar cross-section enhancement. Many existing technologies have limitations in terms of overall gain and scalability to higher frequencies. This thesis presents a new active retro-directive array architecture for Intelligent Transportation System applications such as automotive radar. The topology involves designing a phase-conjugating Rotman lens with reflection amplifiers for increased gain. Components of this architecture can be scaled to mm-wave. A reflection amplifier is prototyped and tested to have a maximum gain of 17.1 dB at 5.3 GHz. The circuit is then augmented onto a phase-conjugating Rotman lens. The amplifiers are tuned to ~ 6.5 dB gain at 5.15 GHz and the overall phase-conjugating performance is assessed. The active eleven element lens has a calculated backscattering gain of 19.2-25.4 dB across the scanning range of ±32 ˚ . Keywords: rotman lens, retro-directivity, phase-conjugation, ITSItem Open Access Advanced Doherty Transmitter Architectures for Wireless Communication Systems(2021-02-02) Zhao, Yulong; Ghannouchi, Fadhel M.; Helaoui, Mohamed; Belostotski, Leonid; Okoniewski, Michal M.Power amplifier (PA) is a critical and energy-consuming building block in wireless communication transmitters. Base stations need to be efficient to minimize the electricity consumption. The wasted energy in wireless transmitters is converted to heat, which degrades the reliability of the system. Over the years, many efficiency enhanced PA architectures have been developed. Due to its good performance and simple structure, the Doherty PA (DPA) has been widely used in base station applications. However, conventional DPA focuses on the design of the amplifier module itself and the needed quarter wavelength transmission line limits the bandwidth of the DPA. In this thesis, first, the high efficiency Doherty transmitter based on the array antenna is proposed and its dynamic load modulation scheme is investigated. The design equations are derived based on the impedance matrix of the generalized load modulation network. The antenna array is then proposed and optimized to achieve the required impedance matrix. The measured results show good performances, which successfully verify the proposed theory and design equations. Second, the dual-branch dynamic reverse load modulation (RMDB) PA is analyzed. Different from the conventional DPA, the carrier PA is a current biased transistor and the peaking amplifier is a voltage biased transistor in the RMDB PA. The working principle of the dynamic load modulation is thoroughly analyzed. To verify the design theory, a Monolithic Microwave Integrated Circuit (MMIC) PA is designed and fabricated using the United Monolithic Semiconductors GH25 process. It is also the first reported MMIC that covers both 4th generation and 5th generation wireless communication frequency bands. Third, to further increase the efficiency of the RMDB PA, the harmonic control technique is implemented in a second MMIC PA design. The constraints of implementing harmonic control in RMDB MMIC PA are thoroughly discussed. By introducing extra offset lines in the carrier and peaking amplifier branches, the second harmonic control was successfully realized. Finally, optimal fundamental load modulation design space for Class-X harmonically tuned power amplifiers (PAs) was studied. Optimal fundamental load trajectories with different sets of second and third harmonic impedances are calculated and verified with harmonic load-pull measurement.Item Open Access Extraction Of Noise Parameters For Single-Ended Components Inside A Differential Circuit Using Single-Ended Equipment(2018-07-09) Huang, Yuxiang; Belostotski, Leonid; Okoniewski, Michal M.; Yanushkevich, Svetlana N.This thesis proposes an approach of investigating electrical and noise parameters of subcomponents inside a fully differential system. To find the single-ended noise parameters, two sets of single-ended noise-parameter measurements and one set of S-parameter measurement are performed. A proof-of-concept PCBs is designed, fabricated, and tested after the algorithms are verified using Matlab. The circuit is designed to have a bandwidth from 500 MHz to 1.5 GHz and be unconditionally stable at all frequencies. The designed circuit has the gain of 9.4 dB at 500 MHz and 9.5 dB at 1.5 GHz in schematic simulations, while in measurements, it has the gain of 8.1 dB at 500 MHz and 4.3 dB at 1.5 GHz. The minimum noise figure is 2.4 dB at 500 MHz and 2.4 dB at 1.5 GHz in simulations, while in measurements, it is 3.1 dB at 500 MHz and 3.2 dB at 1.5 GHz. This thesis presents schematic and measurement results for the electrical and noise parameters. The measurement results are analyzed in Matlab and compared with the relevant single-ended measurement results to verify the operation of the method.Item Open Access Hydration Monitoring using Microwaves: From Modelling and Estimation of Tissue Properties to Validation in Humans(2018-09-21) Garrett, David; Fear, Elise C.; Fear, Elise C.; Okoniewski, Michal M.; Kuo, Arthur D.; Hogan, David B.Dehydration is a prevalent condition which can have profound health consequences. If detected early, it can often be treated by oral fluid replacement. A variety of assessment techniques have been proposed, but none have yet emerged as convenient and accurate indicators. This thesis investigates the use of microwave measurements at the extremities to monitor human hydration, relying on the strong relationship between dielectric properties of tissues and water content. A model describing changes in tissue properties according to dehydration is first developed. We then report an empirical feasibility study in athletes undergoing exercise, demonstrating a relationship between estimated permittivity and weight changes due to water loss. Finally, improved property estimation techniques are introduced which are suitable for reliably detecting changes due to dehydration. This thesis provides a comprehensive initial assessment of how microwave measurements may be used to provide the clinically-demanded method of human hydration assessment.Item Open Access Implementation of General Dispersive Anisotropic Materials in Lebedev FDTD(IEEE, 2018-09-17) Salmasi, Mahbod; Potter, Michael E.; Okoniewski, Michal M.A variant of the finite-difference time-domain (FDTD) algorithm - the Lebedev FDTD method - is augmented to allow for the simulation of electromagnetic waves in general dispersive anisotropic materials. Distinct dispersions may be applied to each of the principal axes of the anisotropic medium. The method is based on the auxiliary differential equation (ADE) and is simple to implement. Because of the collocated nature of the algorithm, multiterm dispersions necessary in previous implementations are avoided. Lebedev grid has previously been studied in detail by different research groups for simulation of anisotropy. In this work, we specifically focus on extending frequency dispersive materials to this method, and provide multiple examples to demonstrate the accuracy, validity and stability of the method.Item Open Access Improving Image Classification Through Generative Data Augmentation(2019-05-15) Nielsen, Christopher Stephen; Okoniewski, Michal M.; Messier, Geoffrey G.; Yanushkevich, Svetlana N.As the industrial adoption of machine learning systems continues to grow, there is incredible potential to use this technology to revolutionize how medical diagnostic imaging is performed. The ability to accurately classify the information contained within a medical image is of critical importance for clinical implementation. Successful application of machine learning classification algorithms has traditionally relied on the availability of copious amounts of labelled training data. Unfortunately, medical datasets are typically small due to privacy constraints and the large cost associated with annotating the data. To ameliorate this limitation, a training scheme is developed in this thesis which can operate on small-scale datasets by using a generative adversarial network to augment the dataset with synthetic images. Through quantifying the uncertainty in the classification network, training samples are selected to maximize the performance of the classifier while minimizing the amount of required data. Furthermore, privacy constraints are preserved as the images sampled from the generative adversarial network are inherently anonymized. The experimental results demonstrate the efficacy in this approach and viability for application in the medical domain.Item Open Access Mathematical Modeling of Heavy Oil Recovery Using Electromagnetic Heating Combined with Solvent Injection(2019-01-11) Sadeghi, Asghar; Hassanzadeh, Hassan; Harding, Thomas Grant; Abedi, Jalal; Okoniewski, Michal M.; Vyas, Rushi J.; Li, HuazhouEfficient heating of oil sands is a challenge in thermal recovery of bitumen. Currently, a standard computational platform for modeling electromagnetic heating combined with solvent injection is lacking and a coupled approach is used. In this approach, a thermal reservoir simulator and an electromagnetic (EM) simulator are coupled to model electromagnetic heating (EMH) combined with solvent injection. This study presents first effort to model the recovery process by developing a standalone electromagnetic heating thermal simulator to simulate the recovery process. The work described in this thesis has two main contributions including development of analytical and numerical models. The analytical contribution includes development of solutions for electromagnetic heating of lossy geological media with applications to bitumen extraction from oil sands. Analytical models are presented for the start-up period of a SAGD-type well-pair for three different scenarios including steam circulation, electrical heating (EH), and EMH-EH. These analytical solutions are then combined with the Duhamel’s theorem to predict the temperature distribution around the horizontal wellbores. The energy efficiency of each scenario is evaluated. The results show that EMH-EH results in a shorter preheating period and is more energy efficient than the current practice of steam circulation. A semi-analytical model was also developed to predict the bitumen production rate, steam chamber growth, and energy efficiency of the process during the vapor chamber development period. The results showed that electromagnetic assisted gravity drainage is less energy intensive than the SAGD. The numerical contribution includes development of standalone two-dimensional, multi-component and multi-phase thermal simulator with an integrated electromagnetic EM component to simulate EM-based bitumen recovery processes. This numerical model integrates full Maxwell’s equation in the frequency domain with variable electrical properties based on temperature and water saturation, coupled with heat and mass transfer in the reservoir. Coupled equations are solved in a fully implicit scheme. The aim of developing a numerical model was to investigate the applicability of high-frequency waves coupled with the solvent as a viable method for bitumen extraction at the field scale. A case study demonstrates the physics of the various phases of the recovery process. The results of the EM-solvent process are compared with the commonly-used conventional thermal recovery method (SAGD) to assess production performance of the two processes in terms of energy efficiency, solvent usage and oil rate. The results reveal that EM-solvent recovery process has potential to eliminate water usage, reduce energy intensity, while recover more oil. These findings reveal that electromagnetic heating is a promising water-free recovery technology for future developments of oil sands resources.Item Open Access Modeling of Antenna Arrays and Mutual Coupling between Array Elements using S-Parameters(2018-03-28) De Silva, Obinamuni Supun Devinda; Belostotski, Leonid; Okoniewski, Michal M.; Fear, Elise C.; Yanushkevich, Svetlana N.An antenna can be modeled as a two-port network using S-parameters. However, having antenna S-parameters are not sufficient for modeling an array of antennas as that requires mutual coupling. This thesis proposes a network model to represent an antenna array including mutual coupling. Using the proposed model, an N-element antenna array can be modeled as a combination of two-port networks to represent each element and an N-port network to represent mutual coupling. In this thesis, the operation of the proposed model is explained and the concept of complete antenna array scattering matrix representation is introduced. Two techniques to calculate mutual coupling S-parameters are presented: primary method using numerical solutions and general method using general expressions. The proposed model was validated with reference to the radiation efficiency and S-parameters between the physically accessible ports using several arrays: various inter-element lengths, varying the number of elements and configurations, and non-identical array elements.Item Open Access A Modular System for Radio Frequency Heating of Hydrocarbon Reservoirs(2019-10-29) Apperley, Thomas; Okoniewski, Michal M.; Nielsen, John; Belostotski, Leonid; Fear, Elise C.; O'Keefe, Kyle P. G.; Bridges, GregRadio frequency (RF) heating is an enhanced oil recovery method with the potential to revolutionize oil sands resource development. In the author's opinion, RF heating currently faces four major practical challenges: heating pattern control, downhole transmission loss, sensitivity to changing reservoir environments and the cost and efficiency of RF generation. This thesis pursues a system concept and laboratory prototypes that can address these issues. The first two challenges can be addressed using a modular system. Sensitivity to the reservoir can be resolved using a single conductor transmission line launcher with two coaxial discontinuities and field quasi-symmetry, which was validated using a frequency-scaled prototype. Power combined switching oscillators can ensure high-efficiency RF generation at high output power, while the use of silicon carbide transistor technology can prospectively reduce cost while providing ruggedness. A new E/Fodd oscillator was devised and a prototype using two power combined oscillators is presented.