Research

The ElectroScience Laboratory (ESL) is a major center of excellence in the Electrical Engineering Department at the Ohio State University. One of the largest such research laboratories in the United States, our faculty and researchers are involved in all aspects of electromagnetics (EM) and radio frequency (RF) technologies, including:

Research Summary

Reconfigurable Slot Aperture Design Concept and Initial Validation
By: Prof. John Volakis, Y. E. Erdemli, and Dr. Kubilay Sertel
Analysis, Design and Evaluation of Complex Stealth Structures
By: Prof. W. Dennis Burnside
UWB Dielectric Antenna Development
By: Dr. Chi-Chih Chen
Optimized Broadband Miniature Antennas via Metamaterial Design
By: Prof. John Volakis, G. Kiziltas, J.H. Halloran, and N. Kikuchi
Antenna Miniaturization And Bandwidth Improvement Using Metamaterials By: Prof. John Volakis, and D. Psychoudakis
U.S. Satellite Industry Computer Code Consortium
By: Prof. W. Dennnis Burnside, Prof. Prabhakar Pathak, Prof. Teh-Hong Lee, and Dr. G. Frank. Paynter
Advanced Methods For Computing Radar Scattering From Helicopters
By: Prof. John L. Volakis, and Dr. Michael Carr
Lattice Electromagnetic Theory via Differential Forms
By: Prof. Fernando Teixeira, and Bo He
Numerical Simulation Of Nonlinear And Nonreciprocal Optical Waveguides
By: Prof. Fernando Teixeira, Dr. B. V. Borges, Dr. A. C. Cesar, and L. D. Alcantara
Advances in Higher Order FDTD Schemes for Large-Scale Electromagnetic Scattering Problems
By: Prof. Fernando Teixeira, Prof. Robert Lee, and Prof. Jin-Fa Lee, and Shumin Wang
Electromagnetic Scattering Simulations
By: Prof. Jin-Fa Lee, Prof. Prabhakar Pathak, Prof. Joel Johnson, and Dr. Robert Burkholder
Electromagnetics Sensors & Systems in the Automotive Industry
By: Dr. Brian A Baertlein, Dr. Ronald Marhefka, and Dr. Jonathan Young
Lattice Electromagnetic Theory via Differential Forms
By: Prof. Fernando Teixeira, and Bo He
Numerical Simulation Of Nonlinear And Nonreciprocal Optical Waveguides
By: Prof. Fernando Teixeira, Dr. B. V. Borges, Dr. A. C. Cesar, and L. D. Alcantara
Advances in Higher Order FDTD Schemes for Large-Scale Electromagnetic Scattering Problems
By: Prof. Fernando Teixeira, Prof. Robert Lee, and Prof. Jin-Fa Lee, and Shumin Wang
Electromagnetic Scattering Simulations
By: Prof. Jin-Fa Lee, Prof. Prabhakar Pathak, Prof. Joel Johnson, and Dr. Robert Burkholder
Mesh Generation and h-version Adaptive Mesh Refinements
By: Prof. Jin-Fa Lee
RF Effects On Electrical And Digital Systems
By: Prof. John Volakis, E. Siah, T. Yang, Dr. Kubilay Sertel1, and V. Liepa
EMI/EMC Optimization for Automotive Applications
By: Prof. John Volakis, E. Siah, D. Psychoudakis, Yakup Bayram, and T. Ozdemir
EM Sheilding
By: Prof. Edward H. Newman
Optical True-Time Delays
By: Prof. Betty Lise Anderson, and Prof. Stuart Collins Jr.
Mapping of Stray Signal Sources in Antenna/RCS Test Ranges
By: Dr. Inder Jeet Gupta
Enhanced Resolution Radar Imaging
By: Dr. Inder Jeet Gupta
RF Systems & Applied Signal Processing
By: Dr. Steven Ellingson, and Grant Hampson
Analysis, Design and Evaluation of Complex Stealth Structures
By: Prof. W. Dennis Burnside
Electromagnetic Measurements Consortium
By: Prof. W. Dennis Burnside
Developments in Reflector Antenna Synthesis and Measurement Control Software at ESL
By: Prof. W. Dennis Burnside, Prof. Teh-Hong Lee, W.H. Theunissen, and others.
R-Card Fences to Eliminate Ground Bounce Term in Antenna/RCS Ranges By: Prof. W. Dennis Burnside, and Dr. Inder Jeet Gupta
Microwave Remote Sensing
By: Prof. Joel Johnson
Detection of Land Mines and Obscured Targets
By: Dr. Brian A Baertlein
Simulation Of Electromagnetic Logging Tools For Oil And Gas Exploration
By: Prof. Fernando Teixeira, Yik-Kiong Hue, and Burkay Donderici
Recent Ground Penetrating Radar Developments
By: Dr. Chi-Chih Chen

Topics

Antennas

The ESL conducts a wide array of research on antennas and radomes, including the development of new mathematical models for computing antenna and radome patterns, implementation of these theories as numerical simulations, and application of simulations and other tools for designing, building, and measuring. Some typical projects that have been considered recently include

• Calculation of antenna patterns on platforms such as aircraft, tanks and boats,

• Development of microstrip and other electrically small antennas,

• Reduction of sidelobes for applications such as radiometry and energy transfer,

• Very-wide-band antennas, operating with high performance from 50 MHz
up to 20 GHz, standing some 13 feet tall,

• Horn antennas with reduced side and back lobes due to construction with special corrugated surfaces, and

• Metal radomes that are essentially transparent at the design frequencies.

Metamaterials

Metamaterials promise unique advances in antenna performance. By using advanced techniques to combine two or more readily available materials, new materials may be developed having any desired electromagnetic characteristics.

Antenna Arrays

Antenna arrays are critical components for many EM systems. The ESL specializes in fast hybrid analysis of large finite arrays, including arrays embedded in multilayer dielectrics. Recently this research has been applied for the analysis of arrays in the Navy’s new DDX stealth ship.

Satellite Antenna Consortium

The ESL Satellite Antenna Consortium is an industry-research alliance to advance the state-of-the-art in satellite antenna design and analysis. Research emphasizes the next generation of satellite antenna design codes and a user-friendly development environment.

Integrated Antennas & RFICs

Integration of antennas with active and passive microwave devices results in self-contained radio frequency (RF) systems. ESL research is developing new integrated systems, as well as reconfigurable integrated antennas, coupled oscillator technologies, and components for RF integrated circuits (RFIC).

Ultra Wideband Radar

Ultra-Wide-Band (UWB) radars, unlike most radar systems that transmit a periodic short burst of energy at a fixed frequency, transmit a more complex signal covering at least a 25% bandwidth. Because of their frequency span, UWB echoes from targets contain improved resolution and extra signature information and are therefore important tools for laboratory scattering measurements. Data from the ESL compact range, which spans 2-18 GHz, is routinely transformed into impulse response signatures and employed in conjunction with advanced signal processing techniques to uncover unique scattering phenomena. One rapidly advancing area for UWB is in remote sensing through foliage and below the surface of the ground. ESL researchers have been active in such Ground Penetrating Radars (GPR) for more than 20 years, with a total of four GPR patents and a nationally known outdoor test field for GPR research. Our present interests in this area include a system for locating chemicals leaking from buried barrels and development of airborne and surface systems to locate unexploded ordnance. Past outdoor UWB research has made use of the Kraus “Big Ear” radio telescope as a base for foliage penetration research. Topics currently being studied at ESL include propagation in complex media, scattering phenomenology, UWB antennas, non-linear space-time and space-frequency processing, and advanced UWB adaptive radar systems.

Integral Equations

Research at the ESL has resulted in significant improvements to the Method of Moments (MoM), a technique that has become the standard for a diverse range of simulation problems including printed circuit antennas, analysis and design of extremely low-frequency shielding, cavity backed antennas, scattering from airborne targets, artificial media, radiation from antennas on platforms such as aircraft and automobiles. The ESL has also employed MoM for analysis of radomes designed for wide bandwidth and minimum distortion of the antenna radiation pattern.

Fast methods for accelerating MoM for electrically large problems are being investigated and applied, such as the Multilevel Fast Multipole Method (ML-FMM). Related integral equation approaches, such as the Adaptive Integral Method (AIM) and hybrid high-frequency Iterative Physical Optics (IPO) techniques for large multi-bounce and cavity scattering problems.

Finite Methods

The ElectroScience Laboratory is well-known for its numerous breakthroughs in advanced finite element and finite difference techniques, such as mesh generation, time-domain simulation, phenomenology computation, special applications, parallelization, preconditioning, and more.

High Frequency Techniques

Recent areas of research in high-frequency methods such as the Geometric Theory of Diffraction (GTD) and its Uniform extension (UTD) include the development of new diffraction coefficients which will permit the GTD to be applicable to a wider variety of perfectly conducting and material structures. This includes radiation, scattering, and coupling problems involving edges, vertices, and curved surfaces such as cylinders, ellipsoids, and spline patches. Gaussian beams are being studied to replace the rays of conventional GTD in order to obtain more accurate and efficient solutions. In addition, time-domain GTD is being developed for its importance in such areas as short pulse radar and remote sensing. Gaussian beam analysis/synthesis and hybrid UTD-Method of Moments techniques developed at the ESL have increased analysis speed and accuracy for complex reflector antennas, realistic aircraft, and large embedded finite arrays, as well as inlet and rough sea scattering.

Automotive Electromagnetics

The automobile of the future will include multiple wireless communication devices and radar systems for impact-avoidance, autonomous navigation, and cruise-control assist. The ESL is active in each of these areas, and our research has contributed new technologies to the industry. The ESL’s active automotive group has developed a variety of new designs for AM/FM, cellular, and global positioning antennas on vehicles, including automotive performance devices such as systems for automotive antenna impedance measurements as well as a rotating automotive turntable for pattern measurements.

Automotive radar sensing is also a major ESL research area. The researchers at ESL have developed a concept for look-ahead radar guidance, using a patented Frequency Selective Surface (FSS) radar strip which is laid on the highway. In partnership with The Ohio State University’s Center for Intelligent Transportation Research, a group of cars for autonomous driving were developed and demonstrated at on I-15 in San Diego, California. Three cars demonstrated autonomous control, including a fully automatic lane change and pass.

Coupling and Interference

Future high-speed wireless systems must be reliable in the presence of both natural and intentional sources of interference. EM Interference (EMI) and EM Coupling (EMC) Research involves analytical, numerical, and experimental efforts to develop "best practices" for future EM shielding designs.

Optical True Time Delays

ESL has developed new designs in optical true-time delays using White Cells. The result is a feed network with very little hardware that can introduce 6,399 different delays for each of 900 antenna elements, improving steering accuracy for wide bandwidth phased array antennas.

Electromagnetic Signal Processing

The ESL’s research in electromagnetic communications began in the 1960s with the advent of communications satellites. Early efforts focused on time division multiple access (TDMA) techniques, propagation of millimeter wavelength signals for meteorological observations, and adaptive antenna techniques. Recently, the ESL has begun working on direction of arrival (DOA) estimation using MUSIC and ESPRIT algorithms, including application of polarization-sensitive antenna elements. Projects at ESL have also studied DOA estimation in multipath environments. Other research in signal processing includes direction finding techniques, time of arrival computation, spectral decomposition, and resolution enhancement for radar target imaging, feature extraction, and more. The ESL has a global reputation in the development and application of modern signal processing techniques to problems in electromagnetics. New radar and antenna imaging techniques have been developed for transforming electromagnetic signals into pictures of the object with an image resolution of ten times that of classical techniques. The ESL also pioneered wavelet analysis techniques for electromagnetic time-spectrum analysis.

Microwave Systems

Innovations in microwave system design using better analog and digital receiver technologies are making new electromagnetic measurements possible. Multi-channel, wide bandwidth, fully coherent systems have been developed and applied in areas such as wireless communications and radio astronomy. The ESL currently possesses a cutting-edge microwave systems laboratory that acts as support for the compact radar range and various microwave system research programs. Recent work revolves around the Hewlett-Packard 8510B and 8753C network analyzers, enabling measurements between 300 KHz to 18 GHz. While these systems are primarily for testing components, they are also being used to develop devices and systems which are not commercially available, including new types of antennas, receivers, transmitters, and controlling apparatus which might be used in satellite communications applications or in certain radar cross section (RCS) measurements. Several graduate students have used the network analyzers while building and testing new pulsed-radar systems for the ESL's compact radar range.

Range Consortium

ESL is a leader in the design and development of compact range and other facilities for precision microwave measurements. The compact radar range at the ElectroScience Laboratory is a state-of-the-art system which can measure the scattering and radiation characteristics of objects as large as eight feet long or as small as a straight pin. Research at the ESL compact range has been so successful that a consortium between The Ohio State University and industry has been organized to study measurement research areas of common interest. In addition, the designs of new systems that have been developed at Ohio State are now being applied to commercial products. The compact range is used to gain a deeper understanding of electromagnetic scattering mechanisms including the relationship of signal frequency and polarization to an object's size and shape. Studies are primarily related to radar and remote sensing systems although there are some important communications aspects for the research as well. As we design and implement improvements to the system, we will still be able to use it for sensitive measurements in order to discover and understand complex new scattering and antennas phenomena.

The Compact Range and accompanying data processing capabilities are available for commercial/defense department use. Both RCS and antenna measurements, relating to current or future research, can be made for interested parties.

Remote Sensing

Microwave remote sensing uses active and passive microwave systems to observe the ocean, atmosphere, terrain, and other environments. Data from these sensors are critical for Earth science and global climate studies. ESL research develops models, techniques, and systems for Earth remote sensing.

Subsurface Sensing

For the past fifty years, the ESL has carried out extensive research into Ground Penetrating Radars (GPR) for detecting and identifying buried targets such as anti-tank (A-T) mines, plastic pipe lines, and tunnels, among others. For example, techniques developed at the ESL for detecting A-T mines have been extended and applied successfully by the British in the Falklands. The ESL is currently developing new sensors and new methods for sub-surface object sensing using active and passive microwave and IR sensors, with emphasis on detection and identification of anti-personnel mines and unexploded ordnance. Both represent major problems in today's world, and continued research will undoubtedly require multi-discipline expertise in areas such as signal processing, civil engineering, and numerical modeling.

Resources Top

Compact Range

The compact radar range at the ESL is a state-of-the-art system which can measure the radar scattering characteristics of objects as large as eight feet long or as small as a straight pin, obtaining complex radar signatures versus polarization, frequency, and target look angle for both non-cooperative target recognition studies and RCS control studies.

OSU has contributed three primary innovations to range technology. The first and most important is the rolled edge on the reflector which allows measurement of eight-foot targets as compared to four-foot targets for the same reflector without the rolled edge. The second innovation represents a collection of efforts to improve the sensitivity while lowering the noise of the chamber. A computer-controlled microwave pulsed transmitter and receiver was developed which has very low power (1/2 watt transmitted) yet is stable enough so that very high sensitivity can be achieved. A new techniqe for time-gating the received signal further improves the sensitivity, and has been shown to be such a successful technique that it is being commercially manufactured today by Scientific Atlanta and Lintek. New radar absorbing materials (RAM) were also developed to more efficiently dissipate unwanted energy before it can reflect off the walls of the chamber.

The third compact range innovation is a new target support structure which is extremely rigid yet virtually invisible to the radar. Consisting of a tilted tapered-wing shape, its internal target rotation apparatus can accurately locate heavy objects while appearing much less visible to the radar than the thin strings used in the past.

The compact range and accompanying data processing capabilities are available for commercial and Department of Defense use. RCS and antenna measurements, relating to current or future research, can be performed for interested parties.

Distributed-Memory Parallel Supercomputer

The ESL’s in-house supercomputer is a cluster consisting of six Itanium 2 processors, each with 9 GB of RAM for a total of 54 GB of available memory. The processors are interconnected via Gigabit Ethernet and facilitate parallel programming via Message Passing Interface (MPI). The machine is lightly loaded to allow short development cycles, yet large enough to allow testing with small- to medium-sized simulations. Once tested locally and found to be stable, large simulations can then be performed on an identical Itanium 2 architecture consisting of 256 processors located at the Ohio Supercomputer Center (OSC).

Northrop Grumman APN-241 Aircraft Weather Radar

Northrop Grumman's (NG) APN-241 combat aerial delivery radar has been operational with the U.S. Air Force since October 1993 and offers the tanker/transport community some of the same advanced technologies originally developed by Northrop Grumman for fighter aircraft. These technologies include high-resolution, ground-mapping modes that enable very precise navigational fixes and aerial cargo drops. The APN-241 also detects wind shear in all weather conditions, meeting the critical safety needs of transport aircraft worldwide, and provides a situational awareness mode for all-weather formation flying. It is the only radar system in production that has been certified by the US Air Force for adverse weather aerial delivery missions. In 2002, Northrop Grumman located an APN-241 radar at the ESL for the purpose of integrating it into OSU’s curriculum. The ESL currently possesses an FCC license allowing the radar’s transmitter to be energized or the radar’s on-board simulation mode can be used in the laboratory environment for a variety of exercies.

Ground Penetrating Radar Range

(Chi-Chih)

Optics Facility

Optical true time delays for phased array antennas.

Phased array antennas suffer from beam squint unless true-time delay is used instead of phase-shifting. OSU's solution is to adapt a well-known optical device, the White cell, to provide thousands of programmable true-time delays for hundreds of antenna elements, with just a handful of mirrors. This hardware-compressive approach uses a microelectromechanical systems (MEMS) array of tilting micromirrors to switch light beams between paths of different lengths. There is one light beam per antenna element, and in the White cell, each light beam make multiple bounces, and is refocused to a new micromirror on each bounce.The final device can fit in a box 4" by 4" by 5".

RFIC Fabrication Facilities

(Roberto)

Automotive Measurements Facility

The ESL has a dedicated automotive measurement facility complete with an outdoor automotive turntable for performing automated antenna radiation measurements from actual antennas on platforms. In recent research projects this facility has been used to design new automotive antennas that are already being incorporated into production vehicles. Future research to be performed at ESL’s automotive measurements facility involves wide-band and antennas hidden within the automobile body, as well as EM coupling and interference studies involving various vehicle systems.

Microwave Measurement Devices

Simulation Codes Top

The ElectroScience Lab has always emphasized the theory as well as the application of numerical techniques. For this reason the most successful and powerful techniques have been implemented in terms of user-friendly computer codes. For example, the Aircraft code (NEWAIR) and the Basic Scattering Code (NECBSC) employ the GTD to compute the radiation patterns of antennas on ships, aircraft, land vehicles and buildings. An electromagnetic surface patch code (ESP) employs the MM to analyze geometries composed of thin wires and polygonal plates, and a reflector code (OSUREF) code uses the GTD to compute the radiation pattern of reflector antennas. Recently the codes have being combined with 3D computer graphics and a modern point-and-click" Motif interface to make their use as simple and intuitive as possible.

ESL Sponsors Top

• John Hopkins University Applied Physics Laboratory (APL)

• Northrop Grumman, Baltimore, Maryland

• U. S. Air Force Research Labs, Dayton, Ohio

• Compact Range Consortium

• USA Satellite Consortium

• Boeing

• MIT Lincoln Laboratory

• Knolls Atomic Power

• Ansoft Corporation

• R & S Associates

• NSF Electrical & Communication Systems

• Systran Federal Corporation

• U. S. Air Force Office Science RES

• Temasek

• NSF Math Sciences

• Air Force Material Command

• Ohio University

• NASA Headquarters

• U.S. Navy

• Harris Corporation

• High Performance Technologies Inc.

• U. S. Air Force Material Command

• Wildblue Communications

• Naval Research Laboratory

• U.S. Army

• Office of Naval Research

• Veridian

• National Science Foundation (NSF)

• Cornell University

• Army Cold Regions Research Engineering Lab

• DSO National Laboratory

• Halliburton

• Lockheed Martin

• Matrix Broadband

• TRW

• Northrop Grumman

• Calearo

• E-OIR Measurements

• VisualEM Corporation

• DARPA

• Laser Tonometer

• Raytheon

• Goodrich

• Applied EM

A list of current unrestricted publications (technical reports and reprints) and order form are available here. To obtain ElectroScience Laboratory reports and reprints please contact reports@esl.eng.ohio-state.edu.

To obtain exportable copies of our electromagnetics codes please send an email request to foreign-codes@esl.eng.ohio-state.edu

To obtain non-exportable copies of our electromagnetics codes please send an email request to usa-codes@esl.eng.ohio-state.edu