Undergraduate Scholarship Recipients

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.