REFTAS Laboratory
Past Students
Neda Nourshamsi
Neda Nourshamsi received the M.S. degree from the University of Strasbourg, Strasbourg, France, in
2014, and the Ph.D. degree from the Oklahoma State University, Stillwater, OK, USA,
in 2018, all in electrical engineering. She is currently working as a Postdoctoral
Research Associate with the School of Electrical and Computer Engineering, Michigan
State University, East Lansing, MI, USA. Her research interests include stochastic
electromagnetics in complex cavities, microwave antennas and propagation, reverberation
chamber theory and antennas propagation.
Thesis Title:
Statistical analysis of electromagnetic complex cavities
Thesis Abstract:
In the last decades, statistical modeling of the maximum electromagnetic (EM) field has been calculated by applying extreme order statistics and the central limit theorem. However, this method only works in the over-moded regime when the parent distribution is known. In this dissertation, the Generalized Extreme Value (GEV) distribution is introduced as an alternative statistical methodology to model the maximum field level directly in different environments such as under-moded regime or a not well-stirred environment. The distribution can converge to three different asymptotic distributions which have different tails (an upper bounded or a fat tail). In order to validate the GEV distribution, mechanical stirring is used inside the reverberation chamber and the equipment under test (EUT) box. The samples from the external stirring follows a Rayleigh distribution. However, locating a small tuner inside the cavity (“internal stirring”) generates a non-Rayleigh distribution. The GEV distribution is applied through samples from internal stirring in both under-moded and over-moded regimes. A maximum likelihood estimator is used to compute the parameters of the GEV distribution. The good agreement between parametric and non-parametric (empirical) samples is achieved which is of interest in the study complex EM cavities. Additionally, the effects of varying the shape parameter of the GEV distribution on the uniformity inside the reverberation chamber are presented. The typical uncertainties inherent inside a nested chamber are also assessed, which are required for statistical modeling. Finally, the GEV distribution has been used to model the maximum field level, while the quality factor of the EUT box has been decreased by locating absorbing material inside the box. This is typically representative of locating electronic devices inside the EUT box. As an additional contribution, we introduce multi-layers perceptron (MLP) as a function approximator to estimate the dimension of materials to have a specific quality factor inside a small cavity. In other words, instead of using random number and dimension of absorbing material, we propose using a neural network to interact the process. A committee of networks and Monte Carlo cross validation are used to improve the performance of the network.
Jacob Dixon
Jacob Dixon was a master’s student at Oklahoma State University in Stillwater, Oklahoma. He graduated
from Oklahoma State in 2015 with his undergraduate degree in Electrical Engineering.
His research interests include unmanned air systems communication integrity, and environmental
studies for communication reliability. Jacob graduated in 2018.
Rahul Bakore
Rahul Bakore received his B.E degree in Electronics and Communication with honors from University
of Rajasthan, India in 2008, and M.S degree in Electrical Engineering from Oklahoma
State University in 2012. His research interests include computational electromagnetics,
electromagnetic compatibility testing, antenna design, RFID. His PhD topic focused
on accurately predicting the electromagnetic fields coupled through the aperture of
an avionics enclosure due to a threat source.
Dipen Das
Dipen Das received his B.Sc in Electronics and Telecommunication Engineering from North South
University, Bangladesh in 2011. He worked at Radio Foorti Inc. Bangladesh as a RF
Engineer before joining MS in Electrical Engineering program at Oklahoma State University
in 2014. He did his MS thesis on Textile antenna designing. His research interest
also included phased array antenna, MIMO and UWB technology. Dipen graduated in 2017.
Ponlakit Jariyatantiwait (Q)
Ponlakit Jariyatantiwait (Q). received his B.Eng. degree in Telecommunication Engineering from King Mongkut’s
Institute of Technology Ladkrabang (KMITL), Bangkok, Thailand in 1998 and M.Eng. degree
in Electrical Engineering from King Mongkut’s University of Technology Thonburi (KMUTT),
Bangkok, Thailand in 2000. He obtained his Ph.D. degree in Electrical Engineering
from Oklahoma State University in 2015. He is currently working at Faculty of Engineering,
Rajamangala University of Technology Phra Nakhon (RMUTP), Bangkok, Thailand. His research
interests include computational electromagnetics, themoacoustic imaging and signal
processing
Ponlakit Jariyatantiwait, PhD. (“Q”) (2015)
Thesis Title:
Computational Study of Microwave-induced Thermo-acoustic Tomography by Time-domain Finite Element Method
Thesis Abstract:
This work presents a time-domain finite element method (TDFEM) for simulation of thermo-acoustic (TA) signal generation in biological tissue for the application of microwave-induced thermo-acoustic tomography (MITAT). This time-domain numerical technique is useful in the analysis of time-varying electric and pressure field generation while a non-conventional microwave pulse excitation in non-homogeneous medium of complex biological tissue structure is applied in this application. In this work, an intensity-modulated chirp pulse at microwave frequency is first applied as an alternative microwave pulse excitation for MITAT. The results of applying the modulated chirp pulse show that the peak-power of microwave pulse can be reduced compared with that of using the conventional modulated Gaussian pulse excitation. In this work, two configurations of acoustic detector array for TA signal detection are considered: concave and convex array, which is a suitable configuration for the application of breast cancer and prostate cancer detection, respectively. The detected TA signal by the array of acoustic detector is processed using a cross-correlation detection in which the propagation (delay) time characteristic of captured TA signal is extracted. This delay time characteristic carries information of the electromagnetic absorption distribution of the tissue in which the back-projection is applied for an image reconstruction. The numerical results of induced TA signal from conventional and modulated chirp pulse are shown. The reconstructed images are compared on the different cases of microwave pulses, detector arrays, tissue properties and geometries.
Sovanlal Mukherjee
Sovanlal Mukherjee is currently a Research Fellow in Medical Physics at Memorial Sloan Kettering Cancer
Center where his research encompasses Deep Learning based Image Classification, Convolutional
Neural Network (CNN) based object detection, Optimization techniques for treatment
planning in Radiation Therapy, Mixed Integer Programming (MIP), and Non-convex optimization.
Sovanlal Mukherjee, PhD. (“Sovan”) (2013)
Thesis Title:
In-silico Study of Trans-rectal Computed Tomography for External and Internal Imaging Geometry
Thesis Abstract:
This work investigates a complete forward and inverse model of thermo-acoustic computed tomography (TACT) for the reconstruction of electrical conductivity distribution within an external and internal imaging geometry. The external imaging geometry that resembles a geometry used for the breast cancer detection and the internal imaging geometry that resembles a geometry used for the prostate cancer detection is illuminated by an electromagnetic (EM) source at a microwave frequency and the generated acoustic wave within the geometry due to EM illumination is detected by an array of ultrasonic transducers. From the detected acoustic wave, the absorbed energy density profile within the geometry and hence the electrical conductivity which is directly related to the energy density is reconstructed. It has been well proved that cancerous tissue exhibits different conductivity profile from normal tissue due to different concentration of ions and water in the cancerous tissue. As a result of this, cancerous tissue absorbs microwave energy differently and a reconstructed image based on an absorbed microwave energy density or conductivity profile can give a precise location of the cancerous tissue. A finite element method (FEM) based complete reconstruction algorithm is investigated and various simulated reconstructed images based on different conductivity profile between cancerous and normal tissue are shown.
Vignesh Rajamani
Vignesh Rajamani is currently Manager at Exponent Failure Analysis Associates in Phoenix, Arizona.
He is the Vice President of Member Services for the IEEE EMC society. He received
the B.E. degree in electronics and communication engineering from the University of
Madras, Chennai, India, in 2002, and the M.S. and Ph.D. degrees with emphasis on statistical
electromagnetics from the Oklahoma State University, Stillwater, OK, USA, in 2004
and 2010, respectively, all in electrical engineering. From 2003–2005 to 2006–2010,
he was a Research Assistant at the REFTAS Lab, Oklahoma State University. In 2005,
he was a Research Associate in the Department of Electrical Engineering and Industrial
Engineering. In 2010, he was a Postdoctoral Research Fellow in the School of Electrical
and Computer Engineering, Oklahoma State University, where he is currently working
as a Visiting Assistant Professor. His research interests include statistical electromagnetics,
antenna engineering, RFID, reverberation chamber operations, validation, and optimization
techniques. He was also involved in building the reverberation chamber at Oklahoma
State University and his current research focuses estimating probability of failure
of electronic systems due to electromagnetic interference and compatibility. a master’s
student at Oklahoma State University in Stillwater, Oklahoma. He graduated from Oklahoma
State in 2015 with his undergraduate degree in Electrical Engineering. His research
interests include unmanned air systems communication integrity, and environmental
studies for communication reliability. Jacob graduated in 2018.
Vignesh Rajamani, PhD. (2010)
Thesis Title:
Establishing Probability of Failure of a System Due to Electromagnetic Interference
Thesis Abstract:
A wire placed inside the metallic box will serve as the equipment under test and the distributions of current and fields will be calculated via measurements. From the distribution, the probability of the observable exceeding a certain threshold can be determined. From the nature of the EME generated, the probability of threat due to EMI can be derived under some assumptions. Combining both the probabilities, the net probability of failure of the system could be determined. Reverberation chambers will be useful in measurements in this study as they simulate operating conditions of the EUT inside a cavity and as the EUT is exposed in all directions to the electromagnetic field, the uncertainty is also reduced. The probability models can provide insight into what type of testing is required to assure worst case testing with reasonable accuracy. The final outcome of this work is to establish the probability of failure due to current coupled onto a cable or a cable bundle located close to the wall of a cavity due to external or internal coupling of EM. The electromagnetic environment of the cavity was determined to estimate the probability of threat depending on the location of the cable inside the cavity. Given that the probability of threat exists, then the probability that the value of the current exceeding a certain threshold was determined. The environment in which the EUT operates and the influence of the environment on the observable that is being targeted was also determined which aids in the calculation of threshold probability. Finally, the net probability of failure of a system was determined from the individual probabilities. The major focus of this work was on the development of the methodology that is sufficiently general to obtain the distribution of any observable. The procedure developed could be used in different scenarios and from a class of distributions developed for each scenario, the probability of threat and probability of failure of a system due to EMI can be calculated.
David Gentry
Hi guys! My name is David Gentry (if you haven't read that already). Right now, I am completing my M.S. degree in
Electrical Engineering at Oklahoma State University. I will graduate in December,
2010. I joined the REFTAS group because I really enjoy learning about electromagnetic
fields. Plus, I would like to have a better understanding of how electromagnetic systems
are designed and built as compared to doing a circuit design. Things that interest
me are: to better understanding the time-domain form of Maxwell's equations, the transient
response of electromagnetic systems, and software that can simulate electromagnetic
systems. My hobbies are coin collecting, watching Stargate SG-1 (the series), and
playing videos games (whenever I have time).
Jakkrit Kunthong
Jakkrit Kunthong received both his BSEE and MSEE in 1998 and 2000 respectively. In 2003 he received
his M.S. in education administration from Cleveland State University, Cleveland Ohio.
He is currently pursuing his Ph.D. degree at OSU, Stillwater Oklahoma. His research
involves characterization of an Anechoic Chamber, characterization of indoor RF propagations,
RFID and Zigbee Active Sensors development. Some of his life long hobbies include
radio control helicopters, ham radio (AA3WK) and open source Asterisk PBX telephone
system (utilizing Voice Over IP technology). He holds the highest class amateur radio
license, Amateur Extra. From Fall 2003 to Spring 2005 he served as the OSU Amateur
radio club president. During this time club membership and participation has soared.
He has been designing, simulating and constructing number of circuits and antennas
used in the ham bands, as well as long distance wireless telecommunication networks
(IEEE 802.11 a/b/g) for many years. You can visit his personal webpage at http://www.aa3wk.net
Ryan Salisbury
Mr. Ryan Salisbury holds a M.S. and B.S degree in electrical engineering, with honors from Oklahoma
State University. He was employed by Sciperio Inc. as a research engineer, where he
worked on numerous projects in the RF realm, and has written several software packages
for electromagnetic optimization of antennas. He has designed size compressed and
impedance matched antennas for many applications, and has designed a complete rectenna
system for 2.4 GHz operation. He has designed, populated, and programmed computer
clusters for distributed optimization of electromagnetic structures. Mr. Salisbury
also helped invent a new antenna, the micro-helix antenna, which is an effective radiator
size compressed to three eighths of a wavelength, and was awarded a patent for this
work. After employment at Sciperio, Mr. Salisbury joined FIO Labs, LLC as both a member
and as Director of Engineering, where his responsibilities included hardware research
and development and project management. Mr. Salisbury designed the hardware, firmware,
and overall system architecture present in the FIO Labs Automated Meter Reader for
water meter systems.
Amjad Awawdeh
Amjad has a B.S. degree in Electrical Engineering (1989) from UAE University and an MBA
from Georgia Southern University (1992). Finished his M.S. in Electrical Engineering
from Oklahoma State University in 2002. He is currently working on his Ph.D. degree
at Oklahoma State University. He also has a work experience of 6 years with hearing
aids located at Oklahoma City. His interests include Image processing, Digital Signal
processing and Wireless Sensors Network. His hobbies include riding motorcycle and
flying.
Cameron Musgrove
Cameron Musgrove is originally from Broken Arrow, OK. He completed his M.S. degree in Electrical Engineering
at Oklahoma State University in 2008 and currently employed at Sandia National Labs.
He completed his B.S. in Electrical Engineering at OSU in December 2005. He was employed
for the Summer of 2005 by a NSF REU with three other students to improve and create
projects for the REAL LIFE classes at Oklahoma State University. He has designed electronics
for and, along with another student, constructed five Laser Diode Power Supplies for
the LASER CULT lab. He is building a RC car control system using a touchpad and 2.4
GHz patch antenna transmitter.
Zijing Wang
Zijing Wang, obtained his BS in Aerospace engineering, MS both in Electrical engineering and
Mechanical/Aerospace engineering. He is now a PhD candidate in electrical engineering.
His research experience and interests include: Computational electromagnetics, Microwave/RF
ciucuit design, Digital signal processing, Wireless propagation, Analysis of machinery
vibration and noise.
Yanzhong Li
Yanzhong Li received his B.Sc. and M.Sc. degrees in electronic engineering from University of
Electronic Science and Technology of China (UESTC), Chengdu, China, in 1990 and 1993
respectively. He got Ph.D. degree in signal and information processing from UESTC
in 2000, and another Ph.D. degree in electrical engineering from Oklahoma State University,
Stillwater, OK, in 2005. He worked as an electronic engineer at the 41st Electronics
Institute of China Electronics Science and Technology Group Company, Bengbu, China,
from 1993 to 1997. Since Feb. 2005, he has been working as a research scientist at
Sciperio, Inc., Oklahoma City, OK. His research interests include radar signal generation
and processing, digital/analog/RF mixed signal circuits and systems, electromagnetic
propagation and scattering analysis, and antenna design optimization.
Zulfiqar Khan
Zulfiqar Ali Khan was born in Sargodha, Pakistan. He received his BS in Electrical Engineering
from University of Engineering and Technology, Lahore in January 1998. From February
1998 to July 2001, he worked as a Research and Development Engineer in the Department
of Electromagnetics and Communication Systems in Advanced Engineering Research Organization
of Pakistan. There he worked on a number of projects including upgrade of a Radio
Communications System, establishing a Telemetry Lab, performing EMC measurements in
a Semi-anechoic chamber and Antenna pattern measurements inside a Compact Range, and
developing a prototype of Sound Pattern Recognition System.He joined Oklahoma State
University in August 2001 and received his MS in Electrical Engineering in December
2003 under the supervision of Professor Charles Bunting. The topic of his MS thesis
was, "Shielding Effectiveness of Metallic Enclosures". Currently, he is working towards
his PhD degree in Electrical Engineering at ElectroScience Laboratory in the Ohio
State University. Mr. Khan is a student member of IEEE, IEEE-EMC, IEEE-APS, IEEE-MTT
and the honor society of Phi Kappa Phi.
Shih Pin Yu
Shih-Pin Yu (S’02) was born in Taipei, Taiwan, R.O.C., in 1975. He received the B.S. degree
in power mechanical engineering from National Tsing-Hua University, Hsinchu, Taiwan,
R.O.C. in 1997 and the M.S. degree in electrical engineering from Oklahoma State University,
Weatherford, in 2003. From 1999 to 2001, he was a Mechanical Engineer with Lite-On
Technology Corporation, Taipei, Taiwan, R.O.C. From 2002 to 2003, he was a Research
Assistant in the School of Electrical Engineering, Oklahoma State University. His
main research interests are statistical electromagnetics, characterization and application
of reverberation chambers.
Amensisa Galelacha
Amensisa Gelalacha received his BS degree in Addis Ababa Univesity, Ethiopia in 2000. Immediately after
his graduation he joined an R&D company, High-Tech Park as Application Engineer. After
working for two years he came to US to take his career to the next level. He was admitted
to Oklahoma State University for his Masters degree in Electrical Engineering. While
he was in OSU he has worked as teaching assistant and research assistant. His thesis
research area was to predict the permittivity and conductivity of layered material
from surface reflection measurement. He graduated from OSU in July 2004 and joined
Abvolt Ltd as Design Engineer. Then he joined National Instruments to pursue his dream
job. He enjoys reading inspirational books, playing guitar, soccer and ping pong.
He believes that "the purpose of Leadership is not to produce followers but leaders".
His future vision is to go back to his home country and bring the glory that is hidden
his nation.
Junho Lee
Junho Lee(S’00-M’04) was born in Seoul in 1974. He serviced for the Korean Army in Kyondki,
Korea from 1995-1997. He received his B.S. degree in Electronic Engineering from Pukyong
National University in 2000. He was employed at Samyoung Telecommunications Co., Ltd.,
Busan as a telecommunication devices maintaining engineer from 2000-2001. He received
the M.S. degree in Electrical Engineering from Oklahoma State University in 2004.
In the Fall of 2004 he joined the faculty of Samsung Electronics Co., Ltd. as an engineer.
His chief interests are fundamental EMI control and Signal Integrity Analysis.
Dena Bymun
Dena Bymun is from Moore, Oklahoma. She attended OSU from 1999 to 2004. Her undergraduate research
in the REFTAS lab during the summer of 2004 consisted of working with a small team
to rebuild the traditional lecture-based electromagnetics field course into an interactive,
team-based class. She also worked on microstrip patch antenna designs for lab research
as well as her senior design project. Her senior design team created a 900 MHz patch
antenna that would transmit data over 1/4 mile. In May 2004 she received her Bachelors
Degree in Electrical Engineering with a Computer Option and a Mathematical Minor.
She is currently an Avionics Engineer and Web Developer for American Airlines.
Zhiqin Zhao
Zhiqin Zhao was born in Hunan, China. He received B. S. and M. S. degrees in electronic engineering
form the University of Electronic Science and Technology of China, Sichuan, and the
Ph. D. degree in electrical engineering from Oklahoma State University, Stillwater,
in 1990, 1993, and 2002, respectively. From 1996 to 1999, he was with the Department
of Electronic Engineering, University of Electronic Science and Technology of China.
From 2000 to 2002, he researched rough surface scattering as a Research Assistant
in the School of Electrical and Computer Engineering, Oklahoma State University. Since
2003, he has been a Post-Doctoral Research Associate with the Department of Electrical
and Computer Engineering, Duke University, Durham, NC. Dr. Zhao is a member of Phi-Kappa-Phi
honorary society and a member of IEEE.