PRISM :: Browsing by Author "Okoniewski, Michal"

Browsing by Author "Okoniewski, Michal"

Now showing 1 - 20 of 49

Open Access
A 460 GHz CMOS Substrate-Integrated-Waveguide Slot Antenna
(2015-09-25) Xie, Hao; Belostotski, Leonid; Okoniewski, Michal
The design of the Cerro Chajnantor Atacama Telescope (CCAT) is progressing within the international astronomical community. This thesis examines the feasibility of using CMOS technology to implement a 460 GHz SIW slot antenna for the CCAT Heterodyne Array Instrument. A 46 GHz broadband high-gain SIW slot antenna was designed and tested to verify the SIW slot antenna design procedure. That design demonstrated good agreement between the simulated and measured results. The antenna has a measured gain of 7.8 dBi at 46.2 GHz and bandwidth of 4.72 GHz. Then design of a 460 GHz SIW antenna was conducted in a 65 nm CMOS process. Several methods were used to simplify the design and simulations: an inductor identification layer was introduced to minimize the design-rule restrictions, and an equivalent dielectric layer was calculated to reduce the computational resource for 3D electromagnetic simulations. The proposed antenna has a gain of 0.09 dBi, efficiency of 29.1% and bandwidth of 25.3 GHz.
Open Access
A cmos-mems probe microsystem for nuclear magnetic resonance force detection
(2009) McFeetors, Gregory E. O.; Okoniewski, Michal
Open Access
A dielectric filled slotline bowtie antenna for breast cancer detection
(2004) Shannon, Christopher James; Okoniewski, Michal; Fear, Elise
Open Access
A flush mounted waveguide antenna for telemetry applications
(2011) Cameron, Trevor R.; Okoniewski, Michal; Fear, Elise
Open Access
A Liquid Crystal-Switched Passive Van Atta Array Element for Millimetre-Wave Automobile Radar Target Enhancement and Concurrent Data Modulation in Adverse Weather Conditions
(2017) Dratnal, Anthony Jan; Okoniewski, Michal; Nielsen, Jorgen; Belostotski, Leonid; Messier, Geoffrey
Severe weather challenges drivers by degrading visibility and road conditions. Modern automotive collision avoidance systems also experience degraded performance in bad weather, which reduces the range of car-mounted sensors that detect obstacles on the road, and of communication networks that warn other cars about hazards. Radar systems are resistant to most weather but remain affected by heavy rainfall, due to regulatory constraints on frequency and power. Radar architectures can improve, but this thesis proposes to enhance the detectability of vehicles by increasing their radar cross sections with a new automotive safety device: a conformal retrodirective patch antenna array installed into car bodywork. A millimetre-wave array element with a novel liquid crystal switch is successfully simulated, fabricated, and experimentally shown to sufficiently modulate the retransmitted radar signal to piggyback data. This guarantees safe detection ranges in worst-case rain showers and replaces secondary communication systems, minimizing environmental RF pollution.
Open Access
A microfabricated rotating element for reconfigurable reflectarray antennas
(2007) Phillion, Rudi Henry; Okoniewski, Michal
Open Access
A Millimeter-Wave Radar and Kinect Depth Camera for Non-Contact Respiratory Sensing
(2013-04-04) Loblaw, Andrew; Okoniewski, Michal; Nielsen, John
Remote, non-contact respiratory sensing has gained interest in the past decade with the dawn of cheaper microwave integrated circuits and optical devices. The need for an inexpensive and portable respiratory monitor is in particular demand in a hospital setting as the respiratory rate provides early warning for cardiorespiratory arrest. This thesis explores the hypothesis that an inexpensive millimeter-wave (MMW) radar module can synergize with an infrared (IR) camera to provide a low-cost module for accurate, long-term measurement of respiratory rate. Both the IR camera system and the MMW radar technique are experimentally validated. Promising results are presented for the IR camera in which the respiratory rate is accurately measured for different scenarios. Measurements with the MMW radar indicate that more expensive and complex hardware are required to achieve adequate results.
Open Access
A modified fingerprinting technique for an indoor, range-free, localization system with dynamic radio map annealing over time
(2012-09-13) Lesser, Andrew M.; Okoniewski, Michal; Nielsen, John
Indoor wireless localization systems have gained considerable interest in the past decade with the wide spread implementation of affordable wireless networks throughout indoor environments. Many organizations have employed these systems to track people, equipment, and merchandise in an effort to reduce operating costs which can include loss or theft, inventory, and efficient utilization of time sensitive assets. The complex, indoor radio frequency propagation environment introduces many challenges for wireless location systems. In particular, the large and small scale fading of signals introduces uncertainties in the location dependence of radio frequency measurements. This thesis explores two approaches to mapping the above location dependency of measurements with the primary focus on reducing the time required for extensive environment calibration. The formulation of proposed location estimation algorithms and calibration approaches will be presented. A radio frequency device affixed to a mock hospital asset will be used as a real world example to validate the algorithms.
Open Access
A Proof-of-Concept Micro-Pneumatically Controlled Reconfigurable Dielectric Resonator Antenna
(2013-09-25) Apperley, Thomas; Okoniewski, Michal
The dielectric resonator antenna (DRA) has several advantages over metallic antennas, which may include low-loss and compact design. However, few frequency reconfiguration methods exist for the DRA. This thesis proposes, designs and validates a new frequency reconfigurable DRA. A proof-of-concept prototype was designed on 101.6 mm x 101.6 mm x 0.508 mm PCB. Frequency reconfigurability was achieved by changing the coupling capacitance between the DRA's fundamental mode and the antenna ground plane by sliding metalized slugs of PCB (3.5 mm x 5.0 mm x 0.29 mm) either under or away from the DRA. The prototype had a measured tuning range of 24.7 % and had two operating frequencies: 21.4 GHz and 16.6 GHz, each with bandwidths of 9.72 % and 6.05 % respectively. The E-plane and H-plane broadside radiation patterns were also measured and were fairly consistent between high and low frequency operation. Keywords: dielectric resonator antennas, frequency reconfigurable antennas
Open Access
Acceleration of finite-difference time-domain electromagnetic simulations using graphics processor units
(2004) Krakiwsky, Sean E.; Turner, Laurence E.; Okoniewski, Michal
The Finite-Difference Time-Domain (FDTD) method is used extensively in microwave engineering and optics for Electromagnetic (EM) simulations. However, FDTD runs too slowly for some simulations to be practical, especially when run on standard desktop computers, but even when run on clusters of computers or supercomputers. The suitability of Graphics Processor Units (GPUs) for the acceleration of FDTD has been investigated. It is demonstrated that consumer GPUs can be used to accelerate two-dimensional FDTD simulations by a factor of roughly seven, relative to compiler-optimized code running on an Intel CPU of similar technology generation. In order to demonstrate this acceleration, an off-the-shelf GPU has been programmed to solve three 2-dimensional electromagnetic problems: (i) a cavity resonator; (ii) a bandgap structure with periodic boundaries; and (iii) a waveguide with ceramic fingers and Perfectly Matched Layer (PML) boundaries. OpenGL is the Application Programming Interface (API) used to program the GPU.
Open Access
Active Rotman Lens Retro-Reflector
(2023-03-23) Kiani Amiri, Hanieh; Okoniewski, Michal; Nielsen, Jorgen S.
A major challenge for automotive radar sensors is establishing a secure connection in inclement weather conditions. This study presents further progress in developing an active-loaded Rotman lens retro-reflector that is designed to alleviate this problem by enhancing the radar cross section (RCS). In this novel structure, a Rotman lens is outfitted with low-power reflection amplifiers to enable overall system gain amplification and modulation. The lens antenna has been equipped with an array of printed Yagi antennas, and its monostatic RCS pattern has been measured. The lens antenna exhibits a nearly uniform RCS pattern between ±35 degrees at 5.15 GHz in both active and passive modes. The active lens structure demonstrates a 7.5 dB increase in RCS while loaded with amplifiers with 8 dB gain. With its high gain, broad angular coverage, and low power consumption, this structure is ideal for low-power RCS enhancement applications, such as mm-wave automotive radar sensors.
Open Access
Analysis and Design of a mm-Wave Wideband LTCC Patch Antenna for 5G Applications
(2022-12-23) Sadeghi, Maryam; Ghannouchi, Fadhel; Sharawi, Mohammad; Helaoui, Mohamed; Okoniewski, Michal
Fifth-generation mobile network (5G) has been planned to meet society's strong data advancement and accessibility. Since the current Long-Term Evolution (LTE) spectrum, i.e., 4G, is crowded and fragmented under 6 GHz, millimeter-wave frequency bands have attracted more interest in deploying 5G networks. The vast amount of unused spectrum in the mm-wave region can support higher data rates required in future mobile broadband access networks. For such significant data rates, wideband systems are required. An appropriate choice is an aperture-coupled patch antenna offering large bandwidth, good cross-polarization, and higher efficiency than conventional microstrip antennas. In mm-wave bands, the losses caused by materials, fabrication tolerances, measurement methodologies, and interconnections between feed lines and the antenna impact the overall performance of the antenna. Accordingly, the interest in fabricating mm-wave antennas using Low-Temperature Co-fired Ceramic (LTCC) is increasing. The LTCC fabrication process, in addition to lower substrate loss and higher fabrication tolerance, enjoys flexibility in realizing an arbitrary number of layers and ease of integration with other circuit components. In this work, a new aperture-coupled patch antenna with wide bandwidth at Ka-band and stable radiation patterns at 28 GHz for 5G applications has been designed, implemented, and tested with Dupont 9K7 LTCC technology. A parasitic patch, embedded air cavity, and large-size aperture improved the bandwidth. Moreover, the embedded air cavity enhanced the gain and reduced losses caused by the surface wave in the mm-wave band. A stripline feed was designed and used, allowing the antenna to be more easily integrated with a beamformer IC in the active array configuration. The impedance bandwidth achieved by the designed antenna is 32%, with a maximum gain of 9 dB at 28 GHz. A broadband Sub-Miniature-Push on Micro (SMPM) coaxial to stripline transition is also developed to feed the proposed antenna. A back-to-back configuration of the transition was fabricated and measured to validate the design. Experimental results showed a good agreement with the simulation results, with a return loss of better than 10 dB and an insertion loss of around 1 dB between 9 to 31 GHz.
Open Access
Analysis and design of printed leaky-wave antennas for broadside radiation
(2009) Sutinjo, Adrian Teguh; Okoniewski, Michal; Johnston, Ronald H.
This thesis describes the analysis and design of two printed leaky-wave antennas (LWA) for broadside radiation. The first design consists of a microstrip transmission line with periodic radiating open stubs. While this type of antenna is not new, a diffrent design approach using t he leaky-wave concept is demonstrated. The advantage of t his approach is additional insight in the antenna radiation behavior through the leaky wavenumber information. A variation of this design, which is facilitated by the leaky-wave concept, is the introduction of reflective terminations in the LWA to attain partial control of t he antenna aperture illumination. Analyses and measurement examples for 50 D, open, and short terminations are described. In the enhances the broadside radiation of the printed antenna while keeping radiation at the horizon low. Alternatively, one may interpret this radiation mechanism through the periodic leaky-wave concept which again provides valuable insight. The details of the analysis, design, and measurement results are described in the thesis. process of the design and measurements of this design, some previously unknown aspects in the broadside LWA involving the beam-splitting condition for finite antenna lengths and measurement distance errors were discovered. These are explained and quantified in detail in the thesis. The second design involves a method to control the usually undesirable surface wave (SW) t hat is excited in the grounded dielectric substrate (GS) by printed antennas, such as printed microstrip patches, printed dipoles, and open stubs as described in the first design. This design makes use of a series of periodic metallic rings of scat terers arranged concentrically around the printed antenna. Though similar in idea to the holographic antenna, this design is an adaptation of t he surface wave based holographic antenna where the SW parameters are more applicable to printed antennas. This is achived by introducing dual phase-shifting metallic dipoles per periodic distance. Using this technique, the SW is re-radiated in such a way that enhances the broadside radiation of the printed antenna while keeping radiation at the horizon low. Alternatively, one may interpret this radiation mechanism through the periodic leaky-wave concept which again provides valuable insight. The details of the analysis, design, and measurement results are described in the thesis.
Open Access
Analysis and Design of Reconfigurable Spiral Antenna for RF Interference Mitigation
(2013-09-05) Kunysz, Waldemar; Okoniewski, Michal; Johnston, Ron H.
Pattern reconfigurable antennas represent an antenna design class that differs from classical fixed-form, fixed-function antennas in that they can reconfigure and adapt their radiation pattern to fit the requirements of a time varying system. The explosion of the variety of satellite applications in the last two decades demands novel, compact antenna designs that allow the capture of ultra-week signals in the presence of RF interference and multipath. Advances in electromagnetic simulation tools and RF/microwave processing technologies have enabled the design of new compact antennas that can be integrated with high quality RF and microwave active and passive components. This dissertation introduces the concept of pattern reconfigurable antenna in a small form factor using novel reactively loaded spiral antennas. The proposed design allows mitigation of reception of intentional or unintentional RF interference sources in the receivers designed for weak (i.e. satellite signal) reception. Two new antennas capable of reconfigurable pattern control are introduced: a dual polarized spiral antenna and x-spiral (cross-spiral) antenna. The novel approach to the creation of sharp nulls in the antenna radiation pattern is presented. The new antenna designs solved various problems associated with classical approach to spiral antenna design and lead to improvements such as lower overall Axial Ratio and higher efficiency/gain at lower end of operating frequency bandwidth. The relevant background work is described and then the design details, computer simulations and measured experimental results are given.
Open Access
Analytical Modeling and Design of High-Efficiency Input-Output Harmonic Tuned Microwave Power Amplifiers
(2020-08-13) Dhar, Sagar Kumar; Ghannouchi, Fadhel; Zhu, Anding; Helaoui, Mohamed; Okoniewski, Michal; Vyas, Rushi
High efficiency power amplifier (PA) is an integral part of an efficient radio frequency (RF) transmitting system design. To enable modern and future wireless communication systems, the quest for efficient, wideband, and linear PA design techniques is ongoing. To cope with the stringent and contrasting requirements of modern wireless communication systems, it is important to consider the practical impairments like device nonlinearity, mismatch, mutual coupling, and channel temperature for high efficiency PA modeling, design, and reliable performance.In this thesis, power amplifier design methodologies have been comprehensively investigated by exploring and exploiting the input and output nonlinearities of the device. In particular, the impact of input nonlinearity on the PA performance is addressed comprehensively, and the efficiency minima phenomenon due to the input and output nonlinearity is demystified. As such, PA design methodologies for high efficiency broadband applications are proposed and verified with low/high power, and/or micro-wave/mm-wave applications. In addition to high efficiency PA design, linearity and output power performance are also investigated. A new input second harmonic design space is proposed in this thesis identifying trade-offs between PA efficiency and linearity performance. This approach led to a new PA topology designated as Class iF-1.In addition, the behavior of a PA and its linearizability by digital pre-distortion (DPD) technique under output mismatch and/or mutual coupling in a modern 5G wireless communication system is studied in this thesis. It has been observed that the PA linearizability is severely impacted by the PA-Antenna interface due to mismatch and mutual coupling. In this context, a new reflection aware unified PA behavioral modeling, and linearization approach is proposed under mismatch and mutual coupling. The proposed modeling technique and linearization approach is verified with a Class AB and a Doherty PA under wide range of output mismatch and/or mutual coupling conditions. Such robust linearization performance under diverse output mismatch and mutual coupling conditions is highly desirable for modern and future communication systems, which are subject to undergoing rapid fluctuations in antenna matching and cross-coupling conditions.
Open Access
Antenna Two-Port Electrical and Noise Parameters
(IEEE, 2016-11) Groves, Patricia; Conroy, Philip; Belostotski, Leonid; Okoniewski, Michal
Noise correlation matrices and noise parameters are useful for low-noise amplifier designers seeking to achieve the best noise performance out of their circuits. In some applications, such as radio astronomy, antennas and antenna arrays are part of receivers and, thus, modeling of the antenna noise is useful. Currently, antenna noise is modeled through antenna efficiency. A more accurate information on the highest-possible antenna efficiency is obtained from its S-parameters or noise parameters. In this letter, we show how the two-port S-parameters of an antenna can be determined by measuring its reflection coefficients inside two specifically sized Wheeler caps, in addition to a free-space measurement. We use the measurement to determine the noise correlation matrices and noise parameters of an antenna. The challenges of constructing appropriately sized Wheeler caps are discussed, and a new way of constructing a Wheeler cap is shown.
Open Access
Antenna-Array Network Model
(IEEE, 2020-03) De Silva, Supun; Okoniewski, Michal; Belostotski, Leonid
An antenna can be modeled as a two-port network using S-parameters. However, having individual antenna S-parameters is not sufficient for modeling an array of antennas as antennas exhibit mutual coupling. This article proposes a network model to represent an antenna array with mutual coupling. Using the proposed model, an N-element antenna array is modeled as a combination of two-port networks representing each element and an N-port network representing mutual coupling. Two techniques to calculate mutual coupling S-parameters are presented: a primary method using numerical solutions and an approximate method using approximate expressions. The proposed model was validated using four monopole arrays having different inter-element spacings, the number of elements, and non-identical antennas.
Open Access
Balanced antipodal vivaldi antenna and dielectric director for breast cancer detection
(2008) Bourqui, Jeremie; Okoniewski, Michal
Open Access
CMOS Parametric Receiver Design for Short-Range and High Data-Rate Wireless Communication
(2021-02-03) Zhao, Zhixing; Magierowski, Sebastian; Belostotski, Leonid; Okoniewski, Michal; Helaoui, Mohamed; Barzanjeh, Shabir; Saavedra, Carlos
With the advent of 5G era, millimeter-wave technologies are drawing increased attention for fast-data-rate communication. Massive RF nodes deployments in 5G require inexpensive RF solutions. Recent RF developments associated with CMOS technologies promise to fulfill such requirements. However, millimeter-wave circuitry on CMOS is still expensive because achieving sufficient power gain requires advanced and costly CMOS nodes. In addition, the conventional way of seeking performance improvements, i.e. reliance on Moore’s law, is approaching its physical limits. In this thesis, parametric circuitry, as an alternative to RF performance enhancement at less-advanced nodes, is investigated. The parametric circuitry exploits varying capacitance to channel RF signal power from one frequency to another. During this frequency translation, an oscillator signal (known as Pump) power is added to the RF signal of interest so that the power gain is realized. The method is unlike a conventional transistor-based amplifier, which is essentially a DC-to-AC power converter. In addition to frequencies, the power gain of the parametric circuit can be tuned by the Pump signal as well. In this thesis, firstly the key technology, i.e. a variable capacitor, on CMOS technology is introduced and discussed. Then, the linearity of a CMOS 1-to-36 GHz parametric upconverter is analyzed. The agreement of the measurement and simulation results with the outcome of the analytic analysis demonstrates that the proposed harmonic analysis method can be relied on for the first-order analysis and quick grasp of design insights. Later, a sub-6GHz parametric downconverter is presented with a power gain of 24 dB. This circuit design shows a promising means to deploy parametric circuits at low-frequency bands.
Open Access
Design of mems capacitive switches for a tunable reflectarray element
(2008) Wu, Billy; Okoniewski, Michal; Potter, Michael E.