Below is a list of the posters (listed alphabetically) presented by our students at the Engineering Graduate Research Symposium. Great work to everyone who participated!
Poster Number: ECE-07
Authors: Jennifer Byford, Premjeet Chahal
Title: 3D Printing Ultra-wideband Hybrid Substrate Integrated Ribbon Waveguides
Abstract: A new wave guiding structure and fabrication technique is introduced for high speed, low loss, ultra-wideband interconnects. It is a hybrid between a dielectric ribbon and a substrate integrated waveguide design. In this structure, a high dielectric constant valued core is surrounded by a low dielectric constant valued cladding which in turn is surrounded by a metal layer. Both cylindrical and rectangular waveguide designs are presented. Simulation and measurement results show that ultra-wide band interconnects with low-dispersion can be designed using this hybrid approach. Fabrication of the cladding layer was carried out using 3D plastic printing. Simulated and measured results are discussed as well as fabrication techniques.
Poster Number: ECE-11
Authors: Michael Craton, Jennifer Byford, Vincens Gjokaj, Premjeet Chahal, John Papapolymerou
Title: 3D Printed High Frequency Coaxial Transmission Line Based Circuits
Abstract: Coaxial transmission lines are among the most elementary high frequency transmission constructions. Their use is ubiquitous in RF and high frequency design and instrumentation, favored for their superior signal isolation. Furthermore, many microwave circuit components are easily implemented using coaxial structures. Filters can be designed with higher Q-factors using coaxial transmission lines as opposed to planar structures (e.g. microstrip). Since the advent of 3D printing, many microwave circuits have been demonstrated, but a coaxial transmission line has not yet been exhibited for high frequency transmission. Current implementations of coaxial transmission lines typically require a dielectric to support the signal conductor. This limits the performance of the waveguide--higher order propagating modes can appear in smaller diameter structures than equivalent air-dielectric geometries. Other implementations use more expensive subtractive manufacturing techniques. For many high frequency designs, it is impractical to use coaxial transmission lines, thus limiting the designer’s flexibility. Semi-rigid coax requires additional tooling and other available coaxial transmission lines can very quickly become prohibitively expensive. 3D printing allows for flexible designs and quick design cycles while also providing an inexpensive design solution. This poster demonstrates a 3D printed coaxial transmission line structure using polyjet printing technology and its implementation in the design of filters for operation up to 10GHz. The unique benefits that 3D printing technology provides make it well suited to address some of the current limitations of coaxial transmission line construction. These techniques provide a template for a coaxial transmission line implementation where it would otherwise not be possible.
Poster Number: ECE-12
Authors: Zane Crawford, Jie Li, Andrew Christlieb, Shanker Balasubramaniam
Title: Advancements in the Mixed Finite Element Method for Electromagnetics
Abstract: The mixed finite element method (MFEM) for electromagnetics use curl-conforming basis functions to represent fields and divergence conforming basis functions to represent fluxes. Previous work on MFEM includes work on solving the coupled Maxwell equations, namely Faraday's and Ampere's law, for the electric field and magnetic flux density. However, the choice of a leapfrog scheme to represent the time derivatives in the coupled Maxwell equations causes CFL-like restrictions on the maximum time step size. Furthermore, a non-uniform spatial grid will cause the time step size to be smaller than needed to resolve the highest frequency content supported by the spatial grid. This can cause a bottleneck for examining wave phenomena, especially in the presence of charged particles, as more time steps must be taken than necessary to see behavior. Recent work has developed alternate time-stepping algorithms for MFEM for the coupled Maxwell equations that have different stability and accuracy properties. More importantly, in this work,we present a MFEM formulation with an unconditionally stable time-stepping algorithm for the coupled Maxwell equations. Additionally, we compare the stability and accuracy properties between leapfrog, Newmark-Beta, and predictor-corrector methods and preliminary work to extend the method to higher order spatial discretizations.
Poster Number: ECE-15
Authors: Vincens Gjokaj, John Doroshewitz, Premjeet Chahal
Title: Design and Fabrication of Multi-frequency Antenna Using Genetic Algorithms for 5G Applications
Abstract: Under on design approach, fifth generation wireless network will converge together most of the available wireless network. To be able to converge all of these bands in a single platform would require multiple antennas placed in close proximity to each other in a highly dense electronic environment. This is not practical and thus design of single antennas that can work at all these frequencies is necessary. Here we propose a patch antenna design that will incorporate most of these bands in a single antenna. To design such an antenna is complex and to overcome the design challenge, in this paper genetic algorithm is utilized to design antenna for design frequency bands and also to achieve high gain, especially at higher frequencies. For the first design, one antenna that can operate in Wi-Fi, Bluetooth, and 4G LTE bands and operate with high gain at all those frequencies is investigated. For the design process, a patch antenna that can operate at the middle frequency band provides the starting point. By pixelating the antenna and then removing certain pixels help provides other bands. Designs that can provide high gain at all frequency bands are determined through multi-objective optimization technique. This paper will present the design of antennas for 5G application using Matlab to run the Genetic algorithm and to control ANYSIS High Frequency Structure Simulator that carried out detailed electromagnetic simulations of different antenna structures. Several antenna designs are fabricated and characterized over a wide-band and their performance is compared to simulated results.
Poster Number: ECE-21
Authors: Saranraj Karuppuswami, Harikrishnan Arangali, Premjeet Chahal
Title: A Hybrid Electrical-mechanical Wireless Magnetoelastic Sensor for Liquid Sample Measurements
Abstract: This poster presents a hybrid passive wireless resonant electrical and mechanical sensor for enhanced sensitivity and specificity. Mechanical resonance measures the viscosity and electrical resonance measures the dielectric properties of liquid samples. The sensor is composed of two magnetoelastic (amorphous ferromagnetic ribbons) strips placed in parallel that are separated with a dielectric spacer forming a capacitor. An inductive coil is attached in parallel to this capacitor leading to an electrical resonant inductive-capacitive (L-C) tank. Both mechanical and electrical resonance frequencies are wirelessly measured using a single pickup coil conntected to an impedance analyzer. Several liquid samples, including food items, having different viscosity and dielectric properties are measured and key advantages of this sensor are demonstrated. This sensor can be used in food quality monitoring and can be integrated with passive RFIDs.
Poster Number: ECE-27
Authors: Mohd Ifwat Mohd Ghazali, Saranraj Karuppuswami, Amanpreet Kaur, Premjeet Chahal,
Title: 3D Printed Air Substrates for the Design and Fabrication of RF Components
Abstract: This paper presents the fabrication and characterization of RF and microwave passive structures on an air substrate using additive manufacturing (3-dimensional, 3D, printing). The air substrate is realized by 3D printing RF structures in two separate pieces and snapped together face to face using a LEGO-like process. Spacers printed on the periphery provides the desired air substrate thickness. Metal patterning on non-planar printed plastic structures is carried out using a damascene-like process. Various RF structures such as low dispersion transmission line, T-line resonator, high gain patch antenna, slot antenna and cavity resonator are demonstrated using this process. Good performance is achieved; for example, measured 50Ω transmission line shows low loss of 0.17 dB/cm at 4 GHz and a patch antenna (center frequency of 4.5 GHz) shows gain and bandwidth of 7.6 dBi and 0.2 GHz, respectively. Details of both measured and simulation results are presented.
Poster Number: ECE-31
Authors: Christopher Oakley, Jennifer A. Byford, Amanpreet Kaur, Premjeet Chahal
Title: Aerosol Jet Printing of THz Passive Components
Abstract: Terahertz systems offer a convenient, non-invasive platform for biomedical imaging, remote sensing, substance detection, communications systems and material characterization. Due to the high cost of system components needed for proper operation such as mixers, filters, polarizers, and amplifiers, large-scale deployment of these systems has not been realized. Additive manufacturing has recently been demonstrated to provide a viable path towards low-cost, rapid fabrication of lenses, waveguides, probes and power splitters for operation in this frequency spectrum. These methods offer many advantages over traditional micromachining and lithographic techniques by reducing the need for a skilled operator, as well as eliminating hazardous waste traditionally generated as a by-product of these fabrication techniques.
Aerosol jet printing of materials allows for a non-contact, direct-write methodology to fabricate structures with feature sizes as small at 10 micrometers, with layer thicknesses of as little as 300 nanometers. Metals, polymers and other materials can be deposited on non-planar surfaces, allowing for the integration of filters and other structures with other components of interest.
The goal of this poster is to demonstrate viability of aerosol jet printing of passive terahertz filters on thin organic substrates. Performance of both band-pass and band-stop printed filters will be compared to similar structures fabricated using traditional lithographic techniques, over several frequency bands.
Poster Number: CMSE-03
Authors: Connor Glosser, Jack Hamel, Shanker Balasubramaniam, Carlo Piermarocchi
Title: Maxwell-Bloch Quantum Electrodynamics: A Full-wave Solution Strategy for Disordered Photonic Media
Abstract: Here we consider a disordered system of interacting quantum dots---nanoscale semiconductors with wide applicability in systems ranging from lasing to quantum computing to biological contrast imaging and next-generation displays. Much like atoms, individual quantum dots facilitate absorptive and emissive processes at specific frequencies over timescales independent of those in the incident radiation. These processes couple between dots due to the presence of electromagnetic fields, giving rise to emergent nonlinear behavior within the system. By treating quantum dots semiclassically within our simulation, we maintain the discrete dynamics inherent to quantum objects without resorting to cumbersome second quantization to describe electromagnetic fields (i.e. fields behave classically). This has the advantage of partitoning the simulation into two distinct parts, (1) determination of source polarizations through evolution of the differential optical Bloch equations, and (2) evaluation of radiation patterns through methods adapted from well-known computational electromagnetics techniques. We employ a highly-tuned predictor-corrector integration scheme to advance (1) in time and the subsequent polarizations serve as pointlike sources to electromagnetic integral equations (chosen to facilitate accurate point-to-point communication of fields without the computational overhead of a ``radiation grid''). The coupled solution of (1) and (2), then, gives a complete description of both the quantum and electromagnetic dynamics at each timestep, giving rise to nonlinear effects such as dynamical frequency shifts, strongly correllated quantum behaviors, and other optical phenomena.
Poster Number: CMSE-04
Authors: Stephen Hughey, Hasan Metin Aktulga, Shanker Balasubramaniam
Title: Parallel Adaptive Fast Multipole Method for Electromagnetics
Abstract: Multiscale electromagnetic (EM) scattering and radiation problems find a wide range of applications in modern engineering design and analysis, from military aircraft to consumer electronics. Integral equation (IE) solutions to these problems are desirable due to their accuracy; however, method of moments discretization of IEs produces dense NxN matrix systems whose solution requires O(N^2) operations in an iterative solver. The fast multipole method (FMM) is often employed to reduce this cost to O(N log N). As the problem size becomes very large, parallelization of the FMM becomes critical.
The FMM achieves this speedup by splitting the simulation domain into a tree of cubes of equal size at each level and having them interact according to a particular set of rules. In the traditional FMM, the densest region of spatial discretization dictates the leaf box size. For multiscale problems, the spatial discretization may be highly non-uniform. Regions outside the densely-discretized region may be over-partitioned, resulting in degradation of the scaling of the FMM.
We describe and demonstrate a set of parallel algorithms that facilitate adaptation of the FMM tree to a non-uniform distribution while preserving the accuracy of the FMM. We define the necessary operators and present an efficient method for handling the cross-level interactions incurred by adapting the tree.
Poster Number: CMSE-05
Authors: Scott O'Connor, Zane Crawford, Shanker Balasubramaniam, John Verboncoeur
Title: Stability Analysis of Dual FIeld Domain Decomposition
Abstract: Electromagnetic simulation tools are critical for many industrial applications. Time domain finite element methods are one class of methods to simulate transient Electric and Magnetic fields. A common approach to solve for both Electric and Magnetic fields in time is to use a leap frog method. In this approach, the electric field is solved at a time step, while the magnetic field is solved at the next half time step or vice versa. These methods have certain stability criterion that dictate various parameters of the simulation; e.g. time step size, mesh size or what range of frequencies can be simulated. One specific method, the Dual Field Domain Decomposition with an Element Level Decomposition (DFDD-ELD), provides a highly parallelizable framework. This work presents a stability analysis of the DFDD-ELD method along with improvements to the method.