Undergraduate Scholarship Recipients

Project Topic: Miniaturized Antennas using Spoof Surface Plasmon Polaritons for IoT Applications

Project Description:This project focuses on developing miniaturized antennas using Spoof Surface Plasmon Polariton (SSPP) phenomenon. SSPPs are electromagnetic waves that propagate along a metal/dielectric interface at low frequencies, mimicking the behavior of surface plasmon polaritons at optical frequencies. The objective of the project is to reduce the size of traditional antennas like Yagi-Uda, travelling wave, and ultra-wideband (UWB) antennas by incorporating structures that excite SSPP waves. The project aims to enhance the performance of antennas for IoT devices and other space-constrained applications maintaining compact designs, with potential applications in wireless technologies.

Project Topic: High-Order Butler Matrix and Its Application to Millimeter-Wave Multibeam Antenna

Project Description: Millimeter-wave multibeam array antenna, which can achieve different beam orientations, is becoming a promising candidate for the future B5G/6G applications for its advantages in high data transmission, wide spectrum and low delay rate. Butler matrix (BM) is a common multiple-input-multiple-output circuit-type beamforming network, which can be integrated with the radiation structure to design multibeam antennas. High-order BMs (for example, 16×16 BMs) cascaded with antenna arrays could produce more beams with higher gain, wider beam coverage and increased beam resolution, which can enhance the communication quality of modern systems. While when the order of the BM rises, the basic components required and the network complexity will increase significantly. To overcome this, the project will explore the possibility of converting high-order BM topology into a lower-complexity form. Furthermore, multi-channel devices and multi-layer solutions will be adopted to realize the integration and miniaturization of high-order BMs.

Project Topic: A low-cost arbitrary polarization detection approach based on energy harvesting metasurface.

Project Description:Polarization matching is vital for electromagnetic wave transmission between the transmitter and receiver. No matter what polarization, polarization detection should be carried out in advance to ensure polarization matching. This project proposes a novel scheme for polarization detection, which exhibits a very low-cost, low-complexity architecture compared to the conventional multiple RF-channel-based method. Two identical EHMs with rectifier are proposed to be deployed on the same receiving plane with orthogonal orientations, which can separately capture the two orthogonal electric-field components of the incident wave and further convert them into alternating-current (AC) signals and finally into direct-current (DC) voltage. A polarization-detection voltage ratio (PDVR) parameter is introduced to characterize the polarization angle versus the two output DC voltages in a monotonic linear manner, providing a high-accuracy polarization angle detection. The proposed approach can be further developed as a sensor, which is promising for polarization detection and polarization tracking of anonymous or non-cooperative radiation sources with slow-time variation properties.

Project Topic: Augmented AI/ML Techniques for the Inverse Design of Multi-Layer RF and Microwave Circuits

Project Description:

In the rapidly evolving field of RF and microwave circuit design, traditional intuition-based methods are increasingly facing challenges due to the growing complexity of high-frequency systems. This project aims to address these challenges by developing a novel approach that integrates physics-augmented artificial intelligence (AI) and machine learning (ML) techniques for the inverse design of multi-layer RF and microwave circuits. The focus is on creating and optimizing convolutional neural network (CNN) models that incorporate RF-specific physics, reducing reliance on large datasets and enhancing the efficiency of the design process. The project will specifically target the design of passive components, such as filters, which are fundamental in transceiver systems and have significant implications for energy efficiency and performance. By employing an AI/ML-based approach, the project seeks to streamline the design process, reduce manual iterations, and open up new possibilities in the design space. The final output will include the implementation and characterization of an RF filter prototype, demonstrating the potential of this innovative methodology in real-world applications.

Project topic: Leaky-Wave Coding Metasurface Antenna for Manipulating Far-Field and Near-Field Radiation

Project Description: Focusing on the next generation of mobile communication scenarios, this project proposes a low-cost antenna scheme designed to replace phased arrays and be applied in near and far field environments

A leaky-wave coding metasurface antenna is proposed that can be used to manipulate the far-field and near-field radiation. The leaky-wave waveguide will operate in the TE10 mode. Slots are arranged on the upper and lower sides of the waveguide at its symmetrical center, and pin diodes are loaded onto these slots. When the diodes are in the “off” state, the slots will radiate, and when the diodes are in the “on” state, the slots will be shorted, resulting in no radiation. The FPGA-controlled diodes enable 1-bit coded control with amplitude states of 0 and 1, as well as phase states of 0° and 180°. Moreover, electromagnetic waves propagate inside the waveguide and generate a propagation phase. By combining the propagation phase with a 1-bit phase, it becomes possible to flexibly select the phase of each antenna element at any location.

Project Topic: Enhanced Motion Sensing With Millimeter-wave Radar and its Biomedical Application

Project Description: The project aims to enhance the motion sensing capabilities of millimeter-wave radar through innovative radar signal processing techniques and to advance its applications in the biomedical field. A novel frequency-reconfigurable technique is proposed to enhance the radar’s motion perception across various scales. Specifically designed for FMCW beat signals, it achieves frequency reconfigurability without any hardware modifications, addressing challenges such as inaccurate circle-fitting, high SNR demand for phase demodulation in weak motion sensing, and velocity ambiguity in large-scale motion sensing. Furthermore, to overcome the limitations imposed by RF leakage on radar motion perception, a time-frequency characteristic-based leakage cancellation technique is introduced. This technique cleverly leverages the frequency-domain characteristics of the intermediate frequency (IF) signal to mitigate leakage through IF compensation using an anti-leakage signal.

Project Topic: Cascaded digital predistortion behavioral models for the linearization of wideband dual-input power amplifiers.

Project Description: The PA plays a crucial role in wireless communications, being a power-hungry component that accounts for a significant dc consumption in base stations. Modern spectrally efficient communication signals present high peak-to-average power ratio (PAPR). This constraint forces the system to operate the PA at a large output power back-off in order to guarantee the required linearity level at the antenna port, leading to a serious degradation of average power efficiency. To minimize power dissipation, highly efficient amplification architectures based on the dynamic load or dynamic supply modulation have been proposed in the literature. For example, the dual-input PA load modulated balanced amplifier (LMBA).

The project proposed delves into the study of digital predistortion (DPD) linearization techniques to ensure the strict linearity demands of modern transceivers, especially with increasing signal bandwidth. The main objective is to compare the single staged polynomial-based models’ linearization performance, with respect to the N-staged cascaded polynomial-based models, when exciting a pseudo-Doherty LMBA with 5G signals presenting bandwidth of hundreds of MHz.

Project Topic: Development of a VNA for Humidity Measurement in Cork Stoppers.

Project Description: In the wine bottling industry, maintaining cork stoppers with a low moisture content (3-8%) is crucial to avoid the unpleasant effects of 2,4,6-trichloroanisole (TCA) in wines. TCA, often described as a moldy or damp smell, is an exceedingly potent chemical and can impart musty scents and tastes to wines.

Traditional methods of measuring cork moisture are either time-consuming or imprecise. To address this, this project proposes a novel approach using resonant cavities to measure cork moisture efficiently. In the quest for a portable and simple measuring system, the aim is to develop a portable system with a Vector Network Analyzer (VNA), that is going to be coupled with a cavity for rapid and accurate humidity measurements, potentially improving the wine quality of millions of consumers.

Project Topic: An open-source modular RF switch matrix for microwave imaging.

Project Description:RF measurements in the microwave range are found to be helpful in imaging breast tissues for tumor detection. Measurements from multiple antennas provides diversity in the data for imaging. To take measurements from many antennas using an instrument with only a few ports, one needs to switch connections by hand or use a switching instrument. Switching instruments are available but are typically expensive, this project will introduce an alternative low-cost electronic switching device. The RF switch matrix will be designed to have a low insertion loss across a wide frequency band of 0.1 – 6GHz. The design will be fabricated on a PCB using a controlled impedance. The switch matrix will also be modular, such that multiple boards can be connected to increase the number of switchable ports.

Project Topic: Development of a Wearable Microwave Sensing Antenna System for Real-time Hemarthrosis Detection and Monitoring.

Project Description: Hemarthrosis is the buildup of blood in a joint, often caused by injury and requires immediate diagnosis within two hours. This project aims to create a microwave sensing antenna system for real-time detection and monitoring of hemarthrosis. The system consists of two main components: the antenna for wideband reception and sensing elements sensitive to capacitive variations in the joint. When designing a wearable antenna, three factors are crucial: understanding the patient’s layer structure compared to healthy individuals, minimizing size for easy skin mounting while maintaining functionality, and ensuring a wide bandwidth for stable communication. A coplanar-waveguide-fed planar design will be used to enhance the excitation of the sensing elements due to its broad-band matching capabilities. This approach will prevent the accumulation of blood in the joint, reducing the risk of inflammation and the development of hemophilic arthropathy.

Project Topic: Diffractionless high-directional transferring of localized electromagnetic signal via microwave hyperbolic metasurface.

Project Description:This project aims to develop microwave metasurfaces with hyperbolic dispersion of surface modes for the efficient and high-directional in-plane transferring of localized electromagnetic signal. The main goal of this research is to increase directionality and propagation length of the localized signal, and to minimize the energy loss within the transferring process, by exploiting the phenomenon of the plasmon canalization and optimizing the design of microwave hyperbolic metasurface. The expected results may be useful for planar photonic devices and antennas, potentially leading to novel applications in surface wave routing and multiplexing.

Project Topic: Development and Design of Broadband Pulse-Based Transceiver Systems at THz Frequencies.

Project Description: My current and future research focuses on the development of broadband pulse-based transceiver systems at THz frequencies. This approach utilizes high bandwidth and can thus provide precise measurements and will contribute to greater resource efficiency in the manufacturing of energy-intensive products such as plastic pipes, hydrogen tanks, and all kinds of sheet or foam materials. Thickness can be measured with high resolution and controlled to a minimum during the process with an inline sensor. In addition, adjustments can be made during production. This saves enormous amounts of energy and raw materials, increases ecological and economic efficiency, and reduces disposal costs. THz transceivers are a sustainable alternative to health-damaging measurement systems based on ionizing radiation currently used in this application area and to expensive and unreliable laser-based THz systems.

Project Topic: Multi-band mixed-signal microwave/mm-wave CMOS transmitter with high power efficiency and linearity enhancement for 6G wireless and SATCOM.

Project Description: This research project is to propose multi-band mixed-signal microwave/mm-wave transmitter with high power, improved linearity, and efficiency enhancement based on advanced-scaling CMOS technology, which can emerge the multi-functional integrated micro-system for 6G wireless and SATCOM applications. A prototype of multi-band mixed-signal microwave/mm-wave transmitter using CMOS technology will be fabricated and measured to verify the proof-of-concept. With investigation of this project, solid theoretical analysis and design procedure for multi-band mixed-signal microwave/mm-wave transmitter will be developed for the multi-functional applications emerging the 6G wireless, SATCOM, etc.

Project Topic: Design of Deep Subwavelength Antennas of VLF Communications.

Project Description: Using piezoelectric materials to construct the radiating elements allows us to dynamically shift an antenna’s resonant frequency into much smaller wavelengths. Recent advances in low-loss and high-efficiency piezoelectric materials have made low-frequency communications and energy harvesting possible. Mechanical antennas printed on or made of piezoelectric materials can operate at resonant acoustic wavelengths up to 10,000 times shorter than the corresponding Electrically Small Antennas. However, placing such small antennas in the vicinity of each other forces a coupling between the reactive fields and leads to much higher radiation than expected by the same number of decoupled antennas. I plan to explore these evanescent field interactions as part of my research project and develop a design methodology for these types of antennas.

Project Topic: Nonlinear Behavior Modeling of GaN Transistors for RF Power Amplifiers Design

Project Description:

An RF power amplifier (PA) plays a key role in an RF transmitter. With the development of wireless communication technology, RF PA design based on gallium nitride (GaN) transistors has become an important research area. As a bridge between the fabrication of transistors and the design of RF circuits, transistor modeling techniques are becoming increasingly popular, both in industry and in academia.My research focuses on the development of nonlinear behavior modeling techniques for microwave GaN transistors and the exploration of the feasibility of using these models for active RF circuit design, particularly for RF PA design. The research aims to extend the working conditions of existing models, and apply them for the design of RF PA circuits. A major benefit of this research is the reduction of GaN device behavior modeling costs. In addition, promoting PA development using GaN behavioral models.

Project Topic: Design of a reconfigurable power amplifier for radar applications.

 Project Description: Reconfigurable RF systems are an increasingly important research field especially for radar systems, where multiple frequency bands, even if not active at the same time (operated, for example, through time-duplexing), would lead to a major increase in the radar capabilities. To this end, reconfigurable matching networks (RMNs) can be used to completely change the frequency response of a device, with just a few electric signals. For this project, different RMNs topologies will be created using GaN-HEMT transistors (as switches) and passive components, and then analyzed to see which one is the most advantageous and flexible. Afterwards, a whole Power Amplifier (PA) will be designed, which must work in at least two different frequency ranges between the C and Ku Band (4÷18 GHz). The final system will incorporate the PA and the most suitable RMNs to maximize performance and efficiency.

Project Topic: A CAD Tool for Design and Analysis of Nonuniform Transmission Lines.

Project Description: Impedance taper or nonuniform transmission line (NTL) is a critical component in microwave engineering, used for matching and transforming the impedance of transmission lines and other passive and active components. Because of wideband impedance matching performance, NTL finds application in the power divider, branch-line coupler and rat-race coupler design. The design and analysis of various kinds of NTLs are crucial for microwave engineers. However, there needs to be a tool/ software available to ease the problem. This motivates the authors to develop a software tool to facilitate the design and analysis of nonuniform taper lines. The software will comprehensively review past and recent developments in impedance taper design, analysis, and optimization, including different types of tapers and techniques. This CAD (Computer Aided Design) tool will be a valuable resource for researchers, engineers, and students working in microwave engineering.

Project Topic: General similarity transformation method for coupling matrix topology and value adjustment

 Project Description: Some filter topologies have multiple coupling matrices that yield the same frequency response. However, currently, there does not exist a systematic method to find these coupling matrices, and furthermore, to identify such topologies. This lack of a method limits the design flexibility of physical filters.

The proposed project aims to find two analytic synthesis processes, A) for synthesizing arbitrary-topology coupling matrices, and B) for synthesizing multiple coupling matrices with the same topology and frequency response. Specifically, it intends to generalize the conventional similarity transformation method for coupling matrix reconfiguration. The result of this project will enable the systematic design of many microwave filters with diverse architectures, expanding the variety of practically designable filters. It will also enable identifying topologies that support multiple (possibly infinite) coupling matrices yielding the same frequency response. Having multiple coupling matrices allows a filter designer more flexibility in selecting physical dimensions.

Project topic: Optimization of the LO Chain of the PLL Synthesizer with Planar Filters to Improve Signal Integrity

 Project Description: The demands of multi-band links in 5G/6G wireless communication necessitate a frequency synthesizer possessing an extensive tuning span and minimal phase noise as well as spectral purity. Our project aims to design  and integrate planar filters into a Local Oscillator chain following a synthesizer to improve the spectral purity of the chain. By strategically designing these compact planar filters, it is possible to mitigate issues such as interference, and frequency harmonics, which can impact the quality of the generated frequency signal. This optimization effort entails refining the performance and quality of the local oscillator chain in communication systems, effectively enhancing overall system performance. Through this integration, we anticipate improvements in signal quality, a reduction in interference and noise, and a consequential enhancement in Radio Frequency (RF) signal reliability, contributing to the robust functionality of the communication infrastructure.

Project Topic: “A Dielectric Permittivity Sensor Based on Inverted Microstrip/3D-Printing Hybrid Technology”

 Project Description: The proposed research topic consists in the development of an innovative sensor for the dielectric characterization of liquid materials. The sensor is based on a section of inverted microstrip line, combined with a channel where the liquid material flows. The structure is fabricated by using a hybrid technology, which integrates the standard printed circuit board technique (to implement the inverted microstrip) with the additive manufacturing (to realize the channel). The dielectric characteristics of the liquid material are retrieved from the variation of the frequency response of the structure (with respect to the case of no liquid). Different materials will be adopted for validating the performance of the sensor, and the retrieved dielectric properties of the materials will be compared with data obtained from commercial devices.

Project Description: This project aims to design, prototype and measure a reconfigurable wearable antenna for multiple Long-Term Evolution (LTE) bands, with strict requirements for the physical size of the device. The goal is to investigate the effect of a body phantom, antenna casing and aperture tuning circuit on the scattering parameters and efficiency of the antenna, and to maintain an acceptable specific absorption rate. With such an antenna design the end-user experience would be hugely simplified, as the health monitoring device can directly utilize cloud computing resources.

Project Topic:  Design of a low-cost compact microwave sensing system for organic tissue analysis

Project Description: Proposed low-cost microwave sensing system is intended for estimating dielectric properties and creating a spatially resolved dielectric image of tissue under test (TUT), which can then be used for detection and localization of possible abnormalities, e.g., malignancies. The designed system consists of a sensing component, a simple affordable, off-the-shelf vector network analyzer (VNA), a portable computer and components for system assembly. A sensing component will be realized as a planar microwave sensor array with split-ring resonators as sensitive elements. The operating frequency range of sensor is expected to be from 0.1 GHz to 6 GHz in order to ensure compatibility with the measuring instrument. Experimental testing will be conducted ex-vivo by using animal and/or artificial tissues, with both low-cost and professional VNA. Different techniques will be tested and employed for extraction of dielectric properties of TUT. Experimental results will be compared with relevant data in order to test the validity of the built system.

Project Topic: Miniaturized, Batteryless and Wireless Medical Implants and Wearables for Stimulation and Sensing.

Project Description:The project aims at developing, optimizing, and refining fully wireless and battery-less implantable and wearable devices for medical stimulation and sensing. The device operation is realized through RF wireless power transfer (WPT) for its various benefits in miniaturization due to its independence from a physical power source like a battery/cell. While the benefits of miniaturization are enabled through WPT, it also poses serious challenges to the ultimate form factor of the device due to depreciating WPT efficiency with miniaturization. This opens a challenging field in microwave theory and circuit design of making highly miniaturized yet efficient methods of WPT using multi-resonant coil, frequency tuning of loops to obtain highly efficient power transfer with small form factors, and co-design of circuits to work with low harvested powers

Project Topic: Design of an Impedance Transforming Circulator.

Project Description: Conceiving fully duplex (FD) communication systems – that operate the transmitter (TX) and receiver (RX) at the same time and frequency – requires antenna interfaces that are compact, lossless, and compatible with CMOS technologies. Non-magnetic CMOS circulators exploiting time variance while breaking reciprocity have shown immense promise for enabling FD communication compared to their magnetic counterparts. The architectures presented thus far in the literature operate with their TX and RX functioning in a 50-ohm interface. In synthesizing highly-efficient standalone power amplifiers (PAs), the associated output impedance has to be as low as possible for optimal operation. Moreover, for achieving an optimal noise figure, the input impedance of an LNA also differs from 50 ohms. Hence, this project intends to leverage the impedance-transforming ability of quarter-wave transmission lines to facilitate the efficient co-design of circulator-PA-LNA transceivers. The proposed circulator will operate at a frequency of 1GHz using tsmc130nm technology

Project Topic: Reconfigurable Intelligent Surfaces (RISs) for Beam Steering Applications

Project Description: Reconfigurable intelligent surfaces (RISs) are expected to form an integral part of the overall architecture of future networks (6G and beyond) owing to their dynamic controllability that helps them to adapt the propagation characteristics of the transmitted signal as per the end requirements. Beam steering is one of the important aspects of such networks, for which RISs are highly suited. Owing to the fact the 6G and future ecosystems operate in a higher frequency band compared to the current standard, the signals are constrained by their low penetrative power, higher path loss, and the phenomena of shadowing. However, by the use of an RIS, an effective means can be provided to change the reflection angle of the transmitted signal in order to ensure that the signal is received without obstruction, and with the desired signal-to-noise (SNR) ratio. Another implication of such kind of control is that it ensures that the incoming signal is received only by the intended receiver, thereby imparting a secure communication pathway between it and the transmitter. The objective of this project is thus to develop a beam-steering device using multiple RIS-based phase shifters, and test the setup in a custom testbed setup.

Project Topic: Harmonic Configurable Time Modulated Array -Based Wireless Power Transfer System with Concurrent Beam Steering and Side Lobe Level Control

Project Description:Abstract—Wireless power transmission is a rapidly growing topic, and its applications ranges from remotely powering an implant within the body to charging a drone for defence application. Phased array antennas are commonly used for beam shaping and steering despite being costly and massive. Phased array antenna’s commercialisation is not a viable possibility and its use in applications requiring stringent scanning is constrained by quantization error. In this proposal, a new Time Modulated Array (TMA) based system that can in principle replace the phased array antenna is presented. TMA arrays may simultaneously perform beam shaping and steering at all harmonics. The proposed system is significantly less expensive than their equivalent since their realization employs inexpensive RF switches. The possibility to employ any power level of the user defined number of harmonics allows us to build a multi-user WPT scenario.

Project Topic: An Efficient Multifeed Antenna for RF Energy Harvesting

Project Description:We developed a multifeed rectenna for high efficiency RF energy harvesting. By using a multifeed slot loop antenna and co-designing the antenna and rectifier circuit, the conventional lossy impedance matching network between the antenna and rectifier was able to be eliminated, thereby boosting the RF-to-DC conversion efficiency. In addition, using multiple antenna feeds extends the high-efficiency working region of the rectifier to realize high DC output power and high efficiency simultaneously.

Project Topic: Near-field dielectric imager using field-modulated standing-wave oscillators for intraoperative tissue imaging.

Project Description:

Tumor margin assessment is a critical step in breast tumor surgery to ensure complete removal. Such a procedure is routinely performed by post-surgical pathological examinations on the excised specimen. A re-excision surgery is often needed if a positive margin is identified  bringing significant discomfort to the patients. Thus, intraoperative imaging that can perform rapid margin assessment (< 5 minutes) at real-time feedback is highly desirable.

This project aims to implement a large size array sensor for imaging on the clinical samples and specifically currently work has accomplished twenty-two pixelated standing-wave oscillators distributing a 22 22 pixels imager array over an area of 5  . Multiple chips will be encapsulated together to extend the field-of-view (FOV) toward 44 44 pixels of a 5mm 5mm imaging area.

Project topic: Realization of a filter-like 3D-printed resonant structure with the aim to develop a cost-effective yet high-performance wireless sensor.

Project Description

This research activity is focused on the implementation of a filter-like 3D-printed resonant structure, with a frequency response having several poles and transmission zeros, to be used for the assessment of the complex permittivity of a solid dielectric material, located in the ideal position, with the purpose of creating a high-performance yet affordable wireless sensor. In order to reduce the vulnerability to fabrication errors and potentially achieve new features in the frequency response of the filters, novel compact resonator designs (such as ridges with changed shapes) will be examined (for instance, a higher number of poles and transmission zeros, or better control of them). The proposed structure will be used for sensing as a result of this research project. In fact, the suggested filter presents some areas where the electric field is rather intense (for example, underneath the ridges), and this effect can be exploited to accurately sense dielectric materials to determine their complex electric permittivity. Based on the fluctuation of the resonance frequency and the quality factor of a cavity resonator, the variation of the frequency response of the filter can be used to determine the electrical characteristics of the material under test more effectively than the conventional method. When perfected, these prototypes can open up new possibilities in the field of wireless sensor networks, thanks to the implementation of tunable filters, and reduced manufacturing costs.

Project Topic: RF/mm-wave passive components based on substrate-integrated defected ground structure (SIDGS).

Project Description:

Aiming at microwave/millimeter-wave applications of 5th-Generation (5G) with low cost and wide frequency coverage, the research on passive components with high integration and low loss rate in the multi-function communication system is proposed in this project. The SIDGS is developed and implemented to allocate the intrinsic fundamental resonance with wideband harmonic suppression and low radiation loss. Besides, passive components (i.e., filter and power divider) with interference suppression are fulfilled based on SIDGS resonant cells. With the investigation of this project, the physical theory and technical foundation will be built and the tunable SIDGS resonator are fulfilled using the theory for its application.

Project Description

Leptin and resistin levels show a good correlation with anthropometric parameters of childhood obesity and its comorbidity. Hence, adipocytokines can be considered as a biomarker of childhood obesity. This work discusses about a free space ex-vivo method to estimate the dielectric properties as well as thickness of brown and white fat tissue in the human body. The technique is based on data acquisition by an ultrawideband time-domain radar and genetic algorithm minimization of the goal function which is the absolute difference between measured frequency-dependent reflection coefficient and its corresponding theoretical value. The SAR value averaged over 1 g of human tissue analysis is also investigated. To mimic the abdomen surface, three layers of the tissue are exploited: a pork skin layer followed by pork fat(lard) and muscle. Metal plate with circular aperture of radius 2 cm is placed on the skin surface to determine the accuracy of the result on a small area of interest on the animal tissue. The proposed technique can be a safe, cost-effective, and portable ex vivo non-contact free space clinical solution for practitioners to determine the level of obesity.

Project Description:

This project is focused on microwave imaging and sensing of dielectric materials. An array of microwave sensors designed based on the complimentary split ring resonators, with each element of the array resonating at a different frequency, is utilized. The array of microwave sensors operates within the range of 1 GHz to 10 GHz. This frequency band allows for data acquisition with cost-effective microwave circuitry that can replace costly vector network analyzers for measurements. Although the frequency is relatively low for high resolution imaging, the acquisition of the evanescent waves in extreme proximity to the imaged object and processing of these waves using near-field holographic imaging allows for obtaining high resolution in cross-range direction. This new imaging and scanning system can be utilized for nondestructive testing of multilayer composite materials, PCB testing, and cancer diagnosis

Project Description:

The arrival of 5G smart devices with peripheral sensors, such as inertial measurement units, cameras, and microphones, are poised to enable mobile, infrastructure-free Synthetic Aperture Radar (SAR) imaging. However, existing smart devices are not capable of producing sufficiently accurate position estimates necessary for focused millimeter-wave (mmWave) imaging. In this project, we will design an algorithm to correct position drift produced by the mobile device by exploiting hidden relationships between the motion tracking error and the correlations between multiple antennas. We will also explore SAR autofocus algorithms to further improve image quality. This design could enable handheld imaging in a wide range of applications, such as non-intrusive package inspection and efficient construction site surveying.

Project Description:

This project aims to design a high-power radiator capable of radiating >-15 dBm total power with an EIRP of 0 dBm at 910 GHz in CMOS. Power oscillator unit cells are designed with fundamental oscillation at 227.5 GHz, and the 4th harmonic at 910 GHz is extracted. A novel antenna coupling scheme is adopted to enable lossless passive synchronization among unit cells. The proposed radiator will comprise of 24 elements which are phase and frequency locked, to boost the total radiated power. On-chip monopole antennas enable radiation, and a high resistivity silicon lens is used to improve radiation efficiency. The circuit is designed in GlobalFoundries 45nm SOI CMOS process.

Project Description:

Rieke diagrams are an important load characteristic of microwave oscillators plotted on a Smith chart. It consists of two families of curves, one representing contours of constant power and the other contours of constant frequency. A Rieke diagram may be used to find the load impedance that provides the optimal balance of power output and frequency stability. An externally adjusted source determines the reflected power, so the magnitude of the reflection coefficient may be increased and become greater than unity. Since the reflection coefficient becomes greater than unity it can no longer be plotted using the conventional Smith chart. A 3D smith chart is a Reimann sphere-based Smith chart that allows plotting circuit parameters whose reflection coefficient magnitude is greater than unity hence overcoming the limitations of the conventional Smith chart. The method of plotting Rieke diagrams of microwave oscillators on a 3D Smith chart using MATLAB (MATrix LABoratory) is discussed in this project.

Project Topic: Characterization of CMOS-compatible GaN-on-Si RF HEMTs by transient S-parameter measurements

Project Description:

This project focuses on the characterization and modeling of dynamic effects in novel GaN-on-Si HEMT prototype devices. To this aim, a tailored experimental set-up must be developed to enable measurements in transient or pulsed regimes, either in a stand-alone configuration, or combined with synchronized RF characterization functionalities, e.g., pulsed/transient S-parameter measurements. Starting from the procedures typically adopted for GaN-on-SiC devices, new characterization procedures tailored to study the dispersive behavior peculiar to GaN-on-Si will be developed. This will allow to identify the involved time-constants, as well as to extract suitable modeling dataset accounting for low-frequency dispersion.

Project Topic: Wearable System for Fluid Distribution Monitoring in the Human Body

Project Description:

Despite the importance of medical imaging to many diagnoses and condition monitoring plans, current techniques remain restrictive. Often, imaging is restrained to sparse intervals, and may be inaccessible to patients due to high-cost or lack of available facilities. The purpose of this project is to expand on an alternative electromagnetic imaging modality that will enable imaging on a 24/7 basis through coils embedded into clothing wrapped around the body. Previous work has shown that a system of two coils wrapped around the limb, placed on either side of a joint, can detect fluid build-up through changes in the complex transmission coefficient in simulation. This project will expand on this work to allow the identification of anomaly location, and validate the system experimentally. Ultimately this system will be fabricated using conductive threads and validated on human test subjects, with the goal of creating a full body wearable system for fluid distribution monitoring.

Project Topic: Implementation of a Multipath Signal Processing Algorithm for a Microwave Transmission System

Project Description:

A microwave imaging system has been developed at the University of Calgary and is undergoing testing for breast cancer treatment monitoring. This project aims to improve upon the signal processing algorithm for this imaging System, by adjusting the processing to implement the effects of multipath on the signals. Microwave imaging systems are low-cost, non-invasive alternatives for medical imaging due to their ability to map the dielectric properties (i.e. permittivity and conductivity) of tissue. It has been shown that malignant tissue displays different dielectric properties than healthy tissue at microwave frequencies. These differences can be used to monitor a patient’s tumor response to cancer treatment. When a signal travels through tissue it can take more than one path from the transmitter to the receiver. This multipath propagation creates a signal with multiple peaks and the analysis of each peak individually gives a better understanding of the different paths the signal is taking through the tissue. Incorporating the multipath information into the system’s permittivity estimations allows for the construction of a more accurate image as it includes data from paths that were originally ignored. This in turn allows the system to more clearly map the composition of and changes in the breast tissue.

Project Topic: Metasurfaces supporting topological states for efficient wave localization at GHz frequencies

Project Description:

Topological edge states’ engineering opens vast opportunities for electromagnetic wave manipulation and creation of devices robust towards the fabrication imperfections and defects arising during the exploitation. The system we consider is described by the extended two-dimensional Su-Schrieffer-Heeger (SSH) model with alternating couplings between the nearest nodes and additional links between the diagonally-opposite nodes. Such a model supports the localization of electromagnetic energy at the corners or edges of the system at specific frequencies. Our goal is to implement this extended SSH model with the help of metasurfaces, which will support topological states at GHz frequencies. The project results may be applied for developing antennas and demultiplexers based on topological metasurfaces

Project Topic: RF/mm-wave passive components with merits of the compact size, low insertion loss, wide operation frequency range, wideband radiation suppression and wideband spurious suppression.

Project Description:

To meet the ever-increasing demands of high data-rate in the wireless communication, this project will propose and implement high performance RF/mm-wave passive component. A series of high-performance filters operating at RF/mm-wave need to be studied and designed in order to satisfy the future wireless communication. Based on the experience of the filter design, more passive components such as power divider, coupler, balun will be investigated and improved to meet the higher requirement. Combining with these passive components, the tunable and reflectionless function are added to gradually realize wide operation frequency. Finally, some on-chip mm-wave multifunction passive components are proposed based on the aforementioned preparation.

Project Topic: Design of a cost effective portable multimode Radar for surveillance application.

Project Description:

During the present pandemic, homeland security has become an issue due to shortage of private security guards. The goal of this project is to design an affordable integrated radar module operating at 2.4 GHz and 24 GHz ISM bands. Then, it can be used as an all-weather sensor for surveillance applications. The sensor works as a frequency-modulated continuous-wave radar. The 2.4 GHz radar works as a long rage radar. As soon as it detects any suspicious activity, the 24 GHz circuit is switched on. A simple Arduino based circuit controls the radar module. A LoRa based gateway is planned to integrate with the module for wireless data transfer to a computing device for further analysis. A smart phone-based app can be developed in future. An AC adapter to DC power distribution unit is under design. Once complete, it can be used as an indoor as well as outdoor sensor unit.

Project Topic: Dissipative plasmonic crystal

Project Description:

Investigation of two-dimensional electron systems is very promising in the development of THz devices. The interest in this area increased dramatically after the seminar work of Dyakonov and Shur, who theoretically predicted that the dc current in the channel of a submicrometer-size field-effect transistor (FET) could become unstable which leads to (i) the excitation of plasma oscillations with the frequency controlled by the gate voltage, and (ii) generation of tunable terahertz (THz) radiation.

Several unsolved problems in the field of plasma waves THz electronics will be investigated. The main objective of the research project is the development of a general theoretical model of optical response of plasma crystals consisting of regions with high and low plasma wave velocity (active and passive regions respectively). We will focus on effects driven by dc electric current. The purpose of our study is to find the resonance frequency shift and the threshold value for the dc current which turns the crystal into the amplification regime, which was recently observed experimentally.

Project Topic: Passive components with interference suppression and low radiation in the multi-standards communication system.

Project Description:

The research project is to propose passive components with interference suppression and low radiation in the multi-standards communication system aiming at the application requirement of 5th-Generation (5G) transmitters with high data rates and high electromagnetic compatibility. In this research project, the SIDGS resonant cell will be the main focus, which is selected to allocate the intrinsic fundamental resonance with wideband harmonic suppression and low radiation loss. Meanwhile, the interference suppression passive components (i.e., filter, and power divider) are fulfilled using the proposed resonator on PCB. With the investigation of this project, the physical theory and technical foundation will be built and the tunable SIDGS resonator are fulfilled using the theory for its application.

Project Topic: 3D Printed Metasurface for Terahertz Orbital Angular Momentum (OAM) Generation  and Multi-Dimensional Multiplexing

Project Description:

Terahertz (THz)-vortex waves featured by different orbital angular momentum (OAM) modes and polarization states hold tremendous potential dealing with the capacity crunch in future ultra-fast wireless communication systems. This project seeks to realize multi-dimensional multiplexing of OAM and polarization in THz domain through a single metasurface by dynamically manipulating the wavefront of electromagnetic waves arbitrarily. The designed THz-OAM metasurface can generate multiple independent channels (corresponding to orthogonal coaxial beams) with OAM modes and orthogonal polarization states by angle-multiplexed technology. The proposed metasurfaces will be additively manufactured by jetting conductive and dielectric inks simultaneously. This project will advance the knowledge of 3D printed customizable THz-OAM metasurfaces with ultrathin profile and conformal shapes. Successful delivery of the project will benefit the predicted future demand in many ways, linking to next-generation wireless communications, Industry 4.0, 5G and beyond.

Project Topic: Wearable UHF RFID Tag Antenna based metamaterial for monitoring and tracking of covid19 patient.

Project Description:

In this project proposal, the passive wearable RFID tag antenna is developed at UHF operating frequency. RFID in UHF band will operate within 860 – 960 MHz with maximum read range of 5 to10 meters. It must be flexible and able to withstand the effects of the human body, to design an appropriate wearable RFID tag. The electromagnetic wave (EM) emitted / received by the RFID tag will be mitigated due to the complexity of the dielectric constant within the human body. Due to the high dielectric constant, the human skin has affected the antenna performance of the wristband. The antenna performance is altered, such as gain, pattern of radiation and impedance. Therefore, tag antenna for free space and a wristband application are designed, analyzed, and made up from meta-material unit consist of split ring resonant. The design of the tag antenna focuses on the compactness and flexibility of wristband.

Project Topic: RF microphone based on millimeter-wave sensing

Project Description:

The project presents an approach to recover sounds based on a compact custom-designed 120 GHz interferometric radar system. The millimeter-wave 120 GHz makes it possible to precisely track the micrometer-scale displacements of vibrating sources such as working speakers as well as other objects vibrated by sound waves such as window glasses in real time. The displacement information recovered with signal processing methods from the radar signals is strictly related to the original audio information and can be recovered to reproduce the sound information. As millimeter-wave 120 GHz has a short wavelength of 2.5 mm, the displacements of the vibrating objects can easily exceed half a wavelength, leading to phase ambiguity. Therefore, a novel algorithm based on trigonometric transform will be employed in this project for millimeter-wave linear phase demodulation.

Project Topic: Full Duplex RF Front-End for 5G Communication Applications

Project Description: This project is circuit design implementation and system-level consideration for next-generation (5G) full-duplex phased-array transceiver (transmit/receive) at 60 GHz. 5G technology provides a high data rate with high bandwidth, low latency, medium-range communication. These features come with some challenges. To address these challenges, RF processing blocks are integrated into advanced BICMOS technology, while each block of the system is implemented by IHP BiCMOS technology. These blocks are power amplifier, low noise amplifier, attenuator, power detector, variable gain amplifier, mixers, phase shifter, SPDT, and SPI. They provide possible solutions to the design of full-duplex RF front-end for 5G at 60 GHz. The applicant contribution to this project is designing phase shifter at 60 GHz within design specifications. These are 11.25-degree phase resolution, 10 dB isolation loss, 5.6-degree RMS phase error rate, and 1.5 dB RMS amplitude error rate.

Project Topic: Ferromagnetic and Ferroelectric Thin Films Enabled Non-linear Circuits for Environment Adaptive Position Independent Wireless Power Transfer Technologies

Project Description: Wireless power transfer (WPT) is an emerging technology with a significant impact in many applications where wired powering is either impractical or inconvenient. However, the power transfer efficiency (PTE) of WPT systems is largely dependent on the coupling factor, which is affected by the environment as well as the position of the transmitting or receiving elements. Several measures have been investigated to reduce the sensitivity of such circuits, but they often involve cumbersome control circuitry. Recently, nonlinear WPT circuits have been developed which decrease the sensitivity of PTE to coupling factor, resulting in simple, cost-effective position-independent WPT circuits. This work studies the use of ferromagnetic and ferroelectric thin film materials which allow for the creation of electrically tunable nonlinear components for use in position-independent WPT circuits.

Project Topic: Frequency-Reconfigurable Rat-Race Hybrid Coupler for Millimeter-Wave and Sub-Terahertz Applications

Project Description: As modern wireless communications continuously increase in speed and performance, operating at higher frequencies has become a requirement and a clear trend for all wireless devices and systems. Simultaneously, multi-band high-frequency communications and advancements in adaptive radio gave rise to the implementation of frequency reconfigurability in integrated devices. High-frequency operation in mm-wave and sub-THz frequency bands renders ultra-wide bandwidths available for frequency allocation, improving the speed and efficiency of wireless systems. Frequency reconfigurability allows wireless systems to be adaptable to different frequencies and communication standards. Combining the benefits of both, we propose a design methodology to devise frequency-reconfigurable rat-race hybrid couplers in the mm-wave/sub-THz range. This project proves itself to be the first implementation of reconfigurable quadrature couplers on silicon at these frequencies. Therefore, the proposed methodology will be a crucial element for the development of next-generation adaptive wireless systems to address beyond-5G/6G challenges.

Project Topic: Design and Implementation of Surface Acoustic Wave (SAW) device in wireless circuit

 Project Description: SAW (surface acoustic wave) filter utilize the electro-mechanical coupling property of piezoelectric crystal. The spacing and design of IDT enable only selected frequency of signal could effectively excites SAW and travels from one port to another port. An in-house design, fabrication and characterization of SAW filter will be conducted. The result of the experiment might shed a light on future optimization of SAW filter and innovative design.

Project Topic: Digital Predistortion of Wideband Power Amplifiers Considering Hardware Limitations

 Project Description: Mobile base stations use a large amount of energy to transmit information. In particular, the device that consumes most of the energy is the power amplifier (PA), whose efficiency is greater at high powers, where an undesirable effect appears, the distortion. On the other hand, new communication standards (4G and 5G) define signals with a high peak to average power ratio (PAPR) that make it necessary to decrease the operating point, with the corresponding decrease in efficiency of the communications device. A very promising solution is digital predistortion (DPD), which consists of processing the transmitted signals in a way that, when they are distorted again by the PA, the cascade block of the DPD and PA results in a nearly linear system. These algorithms must be as efficient as possible and hardware limitations must be considered. The main line of research of this project is the study and development of the effect of hardware limitations on the modeling and predistortion of digital communication systems.

Project Topic: Terahertz time-domain ellipsometry method for cancer diagnostics

 Project Description: Terahertz radiation has some advantages for medical applications. Water has extreme absorption of THz radiation. It allows using water content as effective contrast mechanism. In addition, many molecules exhibit strong absorption in THz frequency range. Due to low photon energy THz radiation is harmless for biological objects. A cancer often causes increased blood supply to affected tissues and a local increase in tissue water content was observed. This fact is a natural contrast mechanism for terahertz spectroscopy of the cancer. The research goal is to develop a method for determination of the polarization properties for the diagnosis of cancer using the terahertz time-domain ellipsometry. The method of THz time-domain ellipsometry allows solving the precise positioning problem that is necessary for THz time-domain reflection spectroscopy. Using the ellipsometry method to obtain the polarization properties of healthy and tumor tissues can enhance the efficiency of cancer diagnosis.

Project Topic: Designing a 5G System for Localization and Communication

 Project Description: The main goal of this project is to investigate the implementation of a 5G communication system for the Internet of Things (IoT) lab on campus. Operating in the 5G band would open the class up for new projects that utilize communication at much higher bands that are insulated from normal Wi-Fi data traffic at 2.4GHz and 5GHz. The first stage of this project is to establish a 16 GHz communication link using commercial off-the-shelf (COTS) components. Analog Devices’ ADAR1000 beamforming chip will function as the heart of the beamsteering network – operating as both a transmitter and a receiver. Constructing the system will begin with manufacturing printed circuit boards (PCB’s) that can properly house the ADAR1000 chip. Once a reliable, line-of-sight communication link has been established, the next step of the project will be to steer the beam to specific points in the room. After the beamsteering capabilities of the system have been established, an upconverter and high-frequency Field Programmable Gate Array (FPGA) will be added to the input of the beamforming network, facilitating the transmission of coherent, modulated data on the beam.

Project Topic: Digital-Assisted Microwave/Millimeter-Wave Transceiver

Project Description: The research project is to design a digital-assisted microwave transceiver aiming at the application requirement of future multi-mode and multi-standard wireless system. In this research project, several key sub-circuits will be mainly focused. Firstly, a dynamic matching network is designed to improve system bandwidth and efficiency. Secondly, self-calibration technique is utilized to eliminate the distortion. Lastly, digital beam forming technology is achieved with precise phase shifters. With the investigation of this project, the solid theoretical and technical foundation will be built for the future communication.

Project Topic: Dielectric Permittivity Sensor Based on Quarter-Mode Resonant Cavities in Substrate Integrated Waveguide

Project Description:

His project activity is related to the design and realization of a dielectric permittivity sensor based on quarter-mode resonant cavities in Substrate Integrated Waveguide technology. The proposed solution allows obtaining performance comparable with non-planar structures, with the advantages of low cost and easy fabrication, typical of the planar ones. The configuration based on a quarter-mode SIW cavity permits to reduce the footprint by 75%, making the sensor attractive for Internet of Things and Wireless Sensor Networks applications.

Project Topic: Self-tuning method for dual-input power amplifiers through machine learning for 5G applications.

Project Description:

The main objective of the research project will consist in designing a self-tuning method for dual-input power amplifiers (PAs), by using machine-learning-based optimization methods. In particular, apply global optimization techniques to find the best configuration for PA biasing, signal calibration and digital predistortion linearization that guarantees the linearity specifications (in terms of Normalized Mean Square Error and Adjacent Channel Leakage Ratio) and maximizes power efficiency of dual-input PAs (e.g., outphasing PAs, load modulated balanced amplifiers), when considering wide-bandwidth signals (hundreds of MHz) presenting peak-to-average power ratios (PAPRs) greater than 10 dB.

Project Topic: Performance optimization of GaN HEMTs by combined RF and LF wideband load-pull.

Project Description:

The behavior of RF power transistors under large-signal operating conditions is determined by the impedance terminations seen by the device at the carrier frequency and its harmonics. Controlling the impedance loads by means of load-pull (LP) allows finding the optimal termination for a given figure of merit, e.g., RF output power or efficiency. However, when wide-bandwidth (BW) modulated signals (e.g., several hundred MHz as envisioned by 5G) are used, passive LP becomes inadequate, and active LP involves complex optimization to concurrently set the wanted terminations at many frequencies points. The project aims at the implementation of drain-port low-frequency (LF) wide-BW LP capabilities within a RF LP bench under development at the EDM-UNIBO lab. In particular, beyond the hardware set-up, the work aims at designing fast iterative optimization algorithms for both LF and RF modulated signal injection targeting maximum linearity and/or power-added efficiency under multi-carrier wide-BW operation. Eventually, by exploiting a generalized active LF LP feature, the set-up involves supply-modulated operation, and the findings would provide the power amplifier (PA) design with optimal control signals for supply-modulated (e.g., envelope tracking) PA architectures.

Project Topic: Liquid Metal in Continuously-Tunable Filter Design

Project Description:

With the expansion of wireless communication services and radar systems, the demand for greater ability to maneuver the already-crowded frequency spectrum is growing. Recently, liquid metal as a tuning mechanism in flexible electronics has been growing in interest due to its high-power handling capabilities, reversibility, repeatability, and ability for continuous smooth change. This project employs the metallic compound Galinstan (GaInSn) in a new tuning mechanism for a substrate integrated waveguide (SIW) bandpass filter. By precisely controlling the insertion height of a liquid metal slug in a center via, the filter can be capacitively loaded with a continuous tuning range. The current aim is to implement fully automated tuning and to refine the design of the tuning method.

Project Topic: Design and Development of Specialized Harmless Antenna for the Fetal and Maternal ECG Monitoring in the Home Setting

Project Description:

This project is about the design and development of a 2.4GHz Bluetooth Low Energy (BLE) directional antenna that is harmless to the human body for the light-weighted device that monitors the ECG signal from both the pregnant woman and the fetus. The aim is to design a modified version of a patch antenna which can be printed directly onto the PCB board as well as being harmless to the side of the human body. It is also needed to ensure the signal quality of the BLE connection since a high bandwidth connection is required in the project to monitor the ECG signal from the woman and the fetus.

Project Topic: Analysis of Pilot Study Data for Microwave Hydration Assessment Validation

Project Description:

Water is vital to many biological functions from temperature regulation to cognitive functions. Even mild levels of dehydration such as 1% body mass loss, can cause both physical and mental impairment. However, currently there is no clinical gold standard that is both convenient to use and accurate. The AEG has developed a prototype hydration assessment system that uses microwave signals to measure the changes in electrical properties of biological tissues as they undergo water loss. In order to validate this system, the AEG has conducted two preliminary studies with human subjects: one using wrestling athletes undergoing acute water loss, and one using participants fasting during Ramadan. This project will focus on analyzing the data from the Ramadan study to quantify system efficacy. During the study, participants were measured throughout the day on three days during Ramadan and three days after. Measure-ments were made with the microwave assessment technique, and weight change and urine concentration were recorded for reference. Statistical analysis of this data will be an important step towards system validation.

Project Topic: Title A reconfigurable dual sense fluidic antenna for Land Mobile Radio and GNSS.

Project Description:

This project is aimed at designing a reconfigurable antenna with dual sense (with linear and circular polarizations) that operates in both the Ultra-High Frequency (UHF) and Global Navigation Satellite System (GNSS) bands. The operation in the UHF band is used for Land Mobile Radio (LMR), whereas its operation in the GNSS frequency bands is can be applied for satellite location tracking systems. The dual sense reconfigurable antenna is aimed to be implemented using fluidic metal (Galinstan) and flexible Polydimethysiloxane (PDMS) substrate, with its reconfiguration enabled using flow control of the fluidic metal. This technique allows the fluidic metal to move into two different radiators embedded in the channels of the PDMS substrate. This generates two antennas that operate with linear polarization (LP) in the UHF band from 330 MHz to 527 MHz, and circular polarization (CP) in the GNSS band with an operating frequency from 1559 MHz to 1616 MHz.

Project Topic: The broadband phase compensator based on metamaterials for terahertz frequency range

Project Description:

Currently, the significant research effort is devoted to developing both broadband and effective optical elements for terahertz radiation. Constructing artificial structures with exotic properties has the huge potential in solving this issue. The main objective of the proposal is to design a new metamaterial device for terahertz application. It’s intended to be a broadband phase compensator and consisted of the metal-striped structure having Drude-model permittivity and ultra-thin liquid layer having Debye-model permittivity in terahertz frequency range. The combination of these two materials will afford to design new metamaterial device without strict narrow-band limitations.

Project Topic: A High-Power, High-Speed, 220 GHz FSK Transmitter Using Coupled Oscillators

Project Description:

As communication systems edge closer and closer to Shannon’s limit in conventional RF bands, new approaches must be taken to accommodate the increased demand for wireless communication throughput. In contrast to the scarcity of bandwidth in RF bands, millimeter-wave frequencies have vast amounts of unallocated spectrum available for high data-rate communication. Millimeter-wave transmitters have already been demonstrated on CMOS processes in several works, but suffer from either high-SNR requirements or high modulation loss. To solve the issue of modulation loss in low-SNR-required modulation schemes, a frequency-shift-keying (FSK) transmitter is proposed. The transmitter is based on a mutually coupled oscillator topology, which allows for frequency tuning with minimal power loss. The topology also exhibits fast-settling frequency modulation, enabling high-data rate communication. This project aims to design a 220 GHz FSK transmitter using coupled oscillators, resulting in a scalable, high-power, 20 Gbps communication system with low SNR requirements and low modulation loss.

Project Topic: Repetitive Control Power Amplifier Linearization

Project Description:

Digital predistortion (DPD) is a popular linearization technique for modern communication systems. The basic conception of DPD is to find the inverse function of the transfer function of the power amplifier (PA) or its equivalent model, and then, DSP or FPGA will be employed to realize the system with this inverse function. The cascade of the predistorter and PA behaves like a linear system. Direct learning architecture (DLA) and indirect learning architecture (ILA) has been proposed, respectively, to identify the parameters of the digital predistorter. However, when the nonlinearity of PA is severe and the noise level is high, traditional DLA and ILA can only provide limited performance. Repetitive control (RC), which is based on the internal model principle, is a time domain algorithm for periodic signal tracking. Assuming that the distortion in a period will appear in the next period, RC algorithm determines related correcting signal, which will be overlaid to the original control signal. Thus, the system can exactly track periodic signals and eliminate harmonics. In this project, RC will be used to realize DPD of a PA, in order to improve the linearity and robustness to measurement noise.

Project Topic: Mitigation of nonlinear effects in communication systems.

Project Description:

Focusing on the application requirements of 5G communication systems with challenging constraints on spectral efficiency, this project will study, develop and implement nonlinear mitigation of wireless communication systems through digital predistortion (DPD) by applying deep learning signal processing techniques.

The complexity of the behavioral models on which DPD is based demands obtaining algorithms that enable a sparse recovery of their coefficients while still enhancing the mitigation procedures in modern wireless systems.

This project will balance the theoretical part of DPD algorithms, implemented in python, with the experimental evaluation of their performance using specialized measurement setups with vector signal generators and vector signal analyzers.

Project topic: Dual-Band Transmitter and Onboard Camera for Experimental Rocket Telemetry Application.

Project Description:

The project consists in designing and manufacturing a complete experimental rocket telemetry system based on a tracking base station. This system will be used to improve the communication with experimental rockets launched by the EirSpace student association of which Mr. Grauwin is a member during the C’Space international student contest organized by the CNES French space agency. The aim of this project is to set up a strong link for data transmission from the rocket to the ground, and create video transmission. All measurements will be transmitted on 138,5 GHz ISM band and a ground station will receive the data. The video transmission will use the 868 MHz ISM band, which allows a better flowrate. Mr. Grauwin will be in charge of designing, manufacturing and testing an 868 MHz emitter based on COST (components of the shelve) as well as a diplexer, a splitter and the dual-band blade antenna. The 138,5 MHz transmitter, the Kiwi Millenium telemetry system, is provided by the CNES.

Project Topic: An high-side wideband current sensor for radio-frequency power amplifiers.

Project Description:

The power efficiency of radio-frequency (RF) power amplifiers (PAs) represents a key aspect in modern transmitters. In addition, increased power dissipation necessitates withstanding higher operating temperatures, which affect the dynamic behavior and reliability of the active devices (i.e. the transistors) within the RF power amplifier. These issues are likely to worsen with the increase of the signals’ modulation bandwidth up to several hundreds of MHz, as planned for future telecom standards (e.g. 5G).

The aim of this project is measuring the dynamic voltage applied to the amplifier’s supply terminal, and the supply current dynamically drained by the amplifier. These measured quantities allow for monitoring the dynamic power dissipated by the device, and at the same time can be used to gain insight into its behavior. This information can then be employed for synthesizing optimal RF signal and supply inputs for the best PA operation. Notably, the bandwidth of both the dynamic supply voltage and supply current can be several times larger than the bandwidth of the RF modulation signal. Whereas the acquisition of wideband dynamic voltage for several hundred MHz bandwidths can be achieved with suitable high-impedance probes, current sensing involves several design challenges.

Project Topic: Electromagnetic engineering of plasmon-assisted optical nanowire sensors for electron beam diagnostics.

Project Description:

The aim of this project is to study the diffraction radiation that accompanies the motion of a modulated sheet of electrons near dielectric and noble-metal nanowire scatterers, in the optical wavelength range. If one can neglect the action of the field on the particles, then the electromagnetic field of such a two-dimensional beam takes form of surface wave propagating along the beam trajectory. This wave induces the polarization and surface currents on the local obstacles and hence a radiation occurs even if the beam does not touch the obstacle. In fact, the scatterer plays role of optical or microwave antenna, which makes the beam of particles visible. In particular, a metal nanowire behaves as an open resonator, thanks to which the diffraction radiation is enhanced near the localized surface plasmon resonance wavelength. Measuring the spatial pattern of the diffraction radiation and its intensity, one can judge about the energy and trajectory of the electrons. This study can be useful in the design of novel sensors of beam position and velocity. It is expected to lead to several conference papers and has potential to be published as a journal paper.

Project Topic: Development of the optically tunable graphene-based THz devices

Project Description:

Since graphene invention, two-dimensional materials have attracted increasing interest in the research community. Graphene has some disadvantages, such as absence of a band gap and low efficiency of material characteristics control by optical pumping. To overcome these disadvantages, another 2D graphene-based modifications were proposed. In this project, the measurements of optical properties of 50-layer graphene under optical excitation will be performed. The tunability of such material is very efficient and it depends on the substrate type, so it can be used in tunable THz devices – modulators, filters, phase shifters, attenuators, etc. These devices based on the suggested material will be developed within this project. The proposed structures will find the application in high-speed THz communication systems, spectroscopy, contactless diagnostics of the objects (such as medication), fast-acting safe visualization systems and in medicine.

Project Topic: Body-worn vest for fully-passive MagnetoCardioGram (MCG) monitoring.

Project Description:

Monitoring human heart-generated electro-magnetic (EM) fields, can be challenging yet critical for detecting heart-related conditions. Comparing two of the most common practices for human cardiac assessment, magnetocardiography (MCG) and electrocardiography (ECG), significant advantages of MCG can be seen, including higher sensitivity and accuracy in response to related conditions, more localized signals, and better deep tissue penetration. However, the widely adopted technology for MCG detection, namely SQUIDs, are bulky, expensive, require extensive shielding and cryogenic cooling -limiting its use for only in hospital/medical environments. The proposed project aims to develop a fully-passive sensor that is unobtrusively incorporated into a wearable vest to monitor human MCG in the pre-hospital environment. The wearable sensor will operate on the principle of changing magnetic flux of the human heart in order to detect the MCG signal. Ultimately, a miniaturized full-passive MCG sensor will be developed, validated and fabricated on a wearable vest.

Project Topic: Teeth Grinding Detection and Intervention using Bone Conduction and Wireless Networks

Project Description:The project targets detection and intervention of bruxism covertly for autistic children with help of integrated sensors and wireless electronics. The proposed solution is a non-invasive, aesthetically benign electronic wrist detector. The device would detect teeth grinding and provide instantaneous wireless feedback to the phone and/or computer through Bluetooth or Wi-Fi connection. The detection mechanism involves the bone conduction of acoustic or ultrasonic signals. The simplified theory applied in our device is that the signal created by bruxism can both be heard (through the air) and transmitted through the bones, demonstrably powerful acoustic conductor. By placing a sensing device at the wrist, the specific signature of grinding teeth could be detected as it propagates through the skull down through the arm. The processed information is delivered to external health professionals who will perform an intervention program to discontinue teeth grinding.

Project Topic: Wireless Power Transfer and Data Communication for Zebrafish ECG Monitoring

Project Description: Zebrafish (Danio Rerio) have extraordinary regenerative abilities and therefore are very useful in numerous biological studies of organ injury. Recently many studies have focused on tracking the zebrafish healing process by monitoring and analyzing Electrocardiogram (ECG) signals. However in most of these studies the zebrafish were sedated in order to obtain the ECG. This would result in affected non-intrinsic ECG readings. A proposed solution to this problem is to measure ECG signals wirelessly through the use of medical implants on non-sedated fish. The implant will be powered, and communicate wirelessly, through inductive-coupling transmitter and receiver antennas. Communication with the implant will be implemented through load modulation. This setup would ensure adequate power and information transfer for the majority of misalignment angles between the transmitter and receiver

Project Topic: Computation of High-Order Electromagnetic Field Derivatives with the Multi-Complex Step Derivative Approximation

Project Description: This research focuses on a novel and efficient technique for the computation of high-order derivatives of electromagnetic field over a broad frequency range. Based on the multi-complex step derivative (MCSD) approximation method, which is free of round-off errors associated with finite difference methods, high-order electromagnetic field derivatives can be computed along with full-wave simulations. The MCSD approximation method is embedded and tested in Finite-Difference Time-Domain (FDTD) simulation, running in parallel with the time-stepping loop, to calculate high-order field derivatives with respect to multi design parameters accurately. The accuracy, stability and computation overhead of the proposed technique is analyzed. In addition to FDTD, the MCSD approximation solver can be further integrated with different simulation methods, introducing a powerful and versatile simulation environment for the applications of sensitivity analysis, uncertainty quantification and multi-parametric modelling of microwave structures.

Project Topic: The development of  chiral metasurface with tunable polarizing properties in THz frequency range.

Project Description: For recent decades the interest to terahertz radiation and its applications in Biophotonics and Biomedicine has increased very high. Despite this, there is a lack of high-quality components, especially polarizing ones. Hence, the aim of my project is to make a tunable polarizer based on chiral metasurface, which could be used in investigations of polarization-changing properties of biological objects, such as cancer, teeth diseases.

A Retrodirective Backscatter Transponder for Intelligent Transportation Systems

With the advent of autonomous systems in the automotive industry, there has been a ubiquitous effort to improve sensor system measurement reliability. Some areas of interest include retrodirective backscattering techniques for vehicle-to-vehicle (V2V) communication and radar cross section enhancement in adverse weather conditions. This project aims to create an active transponder that would be capable of being integrated in both of these applications. The proposed system consists of active low-power reflection gain and microwave lens design combined with a linear antenna array. This prototype is being designed for the licensed Intelligent Transportation System (ITS) 5.85-5.925GHz dedicated short range communication (DSRC) radio band using Keysight ADS and Ansys HFSS simulation. When the performance of the transponder is evaluated the feasibility of scaling it to millimeter-wave automotive frequency bands will be better understood

Signal processing techniques for the linearization of concurrent multiband communications systems

Nowadays, a great research effort is dedicated to standardize the physical layer of the future 5G systems. Definition of waveforms, frequencies and bandwidths is a research challenge that is devised to provide a deep transformation in data transfer, with capacities in the range of Gbps, for which the efficiency vs. linearity trade-off will have an increased impact on 5G transceiver design. The main objective of this proposal is the linearization of nonlinear impairments in modulators, power amplifiers and transmitters, through digital predistortion (DPD). Special attention will be devoted to concurrent amplification and multiband communications. The complexity of behavioural models applied to these cases demands the merge between classical and current signal processing techniques, such as nonlinear adaptive filtering, compressed sensing, principal component analysis, and pruning of regression matrices, amongst others. The project will balance the theoretical proposal of DPD algorithms, implemented in Matlab, with the experimental evaluation of their performance using specialized measurement setups with vector signal generators and vector signal analyzers

Smart microwave phased array transmitter for 5G application

Surrounding the application requirement of 5th-Generation (5G) communication system with merits of low power consumption and high data rates, this project will investigate smart microwave phased array transmitter. In this project, the correction of modulation distortion within a wideband will be the main focus. Wideband power amplifier with digital pre-distortion based dynamic matching network is selected to achieve the high power efficiency with good linearity. Meanwhile, microwave beam forming/ beam-steering will be fulfilled using the reconfigurable multi-bit phase shifter with high phase precision and low power consumption. With the investigation of this project, the solid theoretical and technical foundation will be built for the 5G application.

Design and Implementation of Electrically Tunable Filter on Thin-Films Enabled Engineered Substrate

To miniaturize communication systems, great efforts have been spent on developing tunable RF passives. Fully electrically miniaturized tunable RF passives have been implemented with the integration of both ferromagnetic and ferroelectric thin films directly into the individual specific design. A strategy to improve the ferromagnetic resonance frequency (FMR) of Permalloy to over 6GHz and an electrically tuning method of equivalent permeability for Permalloy with DC magnetic field generated by applied DC current have been developed. A novel engineered substrate implemented with embedded multi-layer Permalloy and lead zirconate titonate (PZT) thin film patterns has been recently investigated and proposed, the substrate has high and DC current tunable permeability and DC voltage tunable permittivity. Miniaturized frequency agile arbitrary RF components could be developed with the proposed electrically tunable engineered substrate combined with state-of-the-art RF design techniques. In this research, it is planned to combine the above two techniques to design, fabricate, and test an electrically tunable filter with the goal of optimizing the resonator structure and the engineered substrate to improve tuning range and performance.

Design and Development of a Bluetooth-based Continuous Blood Pressure Monitoring Device
High blood pressure (BP) or hypertension (HTN) is a common condition which can lead to serious cardiovascular complications if left uncontrolled. The condition requires continuous monitoring of BP and electrical activity of heart (Electrocardiography- ECG) which the existing bulky instruments fail to provide without hindering the patient’s daily activities. This work proposes a home monitoring cuff-less and hassle-free blood pressure wrist-based device that derives BP from photoplethysmography (PPG) and ECG signals, and uses Bluetooth for real-time wireless communication with a smartphone. A user can wear this device as a watch/wristband/armband and the signals are transmitted to a mobile device or computer, possibly connected to a cloud for further analyses and computing. Development of a customized Bluetooth circuit with a printed 2.4-Ghz antenna is crucial for continuous monitoring. Quarter wave patch antenna will be developed and characterized and later incorporated on a flexible substrate.

Wearable Sensors for Elbow Flexion Monitoring
Monitoring elbow joint kinematics after a medical procedure is critical for maximizing/accelerating rehabilitation and preventing future injuries. The most common technologies used to date for monitoring elbow joint kinematics include 3D/2D motion computing cameras and goniometers. However, these technologies are not portable—making it hard for them to capture valuable data in a standard individual’s daily environment. The proposed project seeks to resolve these issues through the development of a lightweight, flexible, and low-cost wearable joint sensor that is embroidered into a textile. These wearable sensors will leverage the principles of magnetic flux in order to measure the flexion of the elbow with high-accuracy and reliability. Additionally, novel methods for powering these wearable sensors are being explored as a way to remove the need for bulky batteries.

Calibration Procedure for Cryogenic Noise Measurements
Accurate calibration of cryogenic noise measurements has been a long standing challenge due to uncertainties associated with thermal gradients along the path between the reference noise source and the device under test (DUT). One approach to address this problem is to perform the measurement using a tunnel junction noise source, which can be operated at the base temperature and whose noise spectrum is well described by basic physical expressions. However, for this technique to work, the insertion loss between the intrinsic tunnel junction and the input of the amplifier must be known. The goal of this research is to develop a methodology for this loss to be systematically determined. A two-tiered VNA calibration procedure will be developed to allow for determination of the gain of each component along the path from the input of the DUT to the input of a spectrum analyzer. As the system is to be operated under vacuum and at cryogenic temperatures, a suite of microwave switches will be employed to make the connections required to perform this two-tiered calibration. Once the gain from the input of the amplifier to the input of the spectrum analyzer is known, it will be compared to the gain determined using the tunnel junction noise source to determine the unknown loss.

A Terahertz Near-Field Measurement System
The project aims at building a near-field platform for antenna radiation pattern measurement at Terahertz frequency. The effect of the measuring probe will be delineated using probe compensation techniques. Due to the fine resolution of the stepper motors, the system can be used for other frequency range up to 1.1 THz. The system can also be used for THz imaging with high resolution and characterization of THz probes for a THz Mueller imaging system for cancer detection by exploiting polarimetry. A THz probes with ±45o linear and left- and right-handed circular polarizations which are not commercially available will also be designed, fabricated, and tested.