Selected NEAR-Lab Electromagnetics Publications & Presentations: L.M. Zurk, “Scattering in Random Media Applied to Terahertz Time Domain Spectroscopy”,

Selected NEAR-Lab Electromagnetics Publications & Presentations:

L.M. Zurk, “Scattering in Random Media Applied to Terahertz Time Domain Spectroscopy”, (invited presentation), Progress in Electromagnetic Research Sym. (PIERS), Beijing, China, Mar. 2007

L.M. Zurk, B. Orlowski, G. Sundberg, D.P Winebrenner, E.I Thorsos, A. Chen, “Electromagnetic Scattering Calculations for Terahertz Sensing”, Proc. of SPIE, San Jose, CA, Jan. 2007

L.M. Zurk1, B. Jouni, F. Farahbakhshian, D.P. Winebrenner, E.I. Thorsos, A. Chen, M. R. Leahy-Hoppa, L.M. Hayden, “Scattering Calculations for Evaluation of Terahertz Detection of Explosive Material”, Seventh International Symposium on Technology and the Mine Problem (MINWARA), Monterey, CA, May 2006

R. Toengi, “Airborne Synthetic Aperture Radar (SAR) Terrain-Based Processing”, MS Thesis

L. M. Zurk, S. Matzner, F. Farahbakhshian, R. Toengi, "Electromagenetic Modelling for Interpretation of Airborne SAR Imagery," PIERS, Cambridge, MA, March 2006.

L. M. Zurk, B. Jouni, F. Farahbakhshian, "Calculation of Scattering from Polyethylene Particles Compared with Terahertz Measurements," PIERS, Cambridge, MA, March 2006.

S. Matzner, L. M. Zurk, A. I. Timchenko, "Radar Detection of Subsurface Objects Using Correlation Imaging," PIERS, Cambridge, MA, March 2006.   

A. I. Timchenko, L. M. Zurk, "Signal Processing Methods for Detection of Subsurface Objects by Ultra-wideband SAR," IEEE GRS, Korea, July 2005.

Electromagnetics Research Projects:• Scattering models for Synthetic Aperture Radar• Correlation processing for detection of land mines• Rough surface scattering from target multipath• Terahertz imaging for explosive detection and biomedical imaging

NEAR-Lab Research involves numerical modeling, development of theory, and participation in large-scale collaborative experimentation efforts

Coupled grain scattering: random media models (“Swiss cheese” model)

HMX explosive granular structure(image from LLNL UCRL-PRES-

150298)

Research Spotlight: Terahertz ImagingUntil recently, little was known about properties of the terahertz region (terahertz = 1012, between microwave and visible) of the electromagnetic spectrum, earning it the title of the “THz Gap”. However, recent advances in ultrafast optics have provided the means to generate and measure THz signals, and this has opened the possibility of THz sensing with a multitude of potential applications. Two of the most promising – detection of explosive materials and biomedical imaging – are being actively explored in the Northwest Electromagnetics and Acoustics Research Laboratory (NEAR-Lab). The research is supported by grants from the Office of Naval Research (ONR) and the National Science Foundation (NSF), and is in collaboration with the Applied Physics Laboratory at the University of Washington.

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The NEAR-Lab focus is on the modeling and analysis of electromagnetic and acoustic wave phenomenon for development of advanced signal processing techniques. The understanding of wave scattering provides a basis to devise and evaluate advanced signal processing algorithms for applications such as radar, sonar, and biomedical imaging.

Northwest Electromagnetics & Acoustics Research Laboratory Dr. Lisa Zurk, Director http://nearlab.ece.pdx.edu/

NEAR-Lab

Comparison of Synthetic Aperture Radar (SAR) image with optical image (SAR image is from the MIT Lincoln Multi-mission ISR

Testbed, LiMIT)

Scattering models for correlation processing applied to radar detection of land mines; exploits structure of signature from

buried object (collaboration with Dr Timchenko, Inst. RadioPhys., Ukraine)

Comparison of NEAR-Lab rough surface scattering codes

Direct Target-Ground

Ground-Target Ground-Target-Ground

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)2(

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)(2

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Radar multipath modeling(collaboration with MIT)

Data and model comparison showing experimental scattering by Large Grain PE (LGPE) versus Small Grain PE (SGPE) explained well with dense media theory, Quasi-crystalline approximation (QCA)(Data provided by University of Maryland, Baltimore County)

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Selected NEAR-Lab Acoustics Publications & Presentations:

L.M. Zurk, J. Quijano, M. Velankar, D. Rouseff, “Bistatic invariance for active sonar systems”, Acoustical Society of America (ASA), Honolulu, HI, Jan 2007

L.M. Zurk, J. Lotz, T. Ellis, J. McNames, J. Ecochard, “Sonar mapping for coral reef conservation”, ASA, HI, 2007

J. Quijano, L.M. Zurk, A. Turgut, D.J. Tang, “Ocean bottom scattering: characterization with chirp sonar”, ASA, HI, 2007

L. M. Zurk, D. Rouseff, G. Greenwood, "Bistatic Invariance Principle for Active Sonar Geometries," European Conference on Underwater Acoustics (ECUA), Carvoviero, Portugal, June 2006

J. Quijano, Use of the Invariance Principle for Target Tracking in Active Sonar Geometries”, MS Thesis

J. Quijano, L.M. Zurk, “Use of the invariance principle for target tracking in active sonar geometries”, IEEE Oceans, Providence, RI, 2006

L. M. Zurk, B. H. Tracey, "Depth-shifting of guide sources," Oct 2005, JASA, N118 (4).

L. M. Zurk, "Guide Source Depth and Range Translation for Robert MFP," ASA, Minneapolis, October 2005

M. R. Velankar, L. M. Zurk, "Mode-Based Adaptive processing in uncertain environments," ASA, Minneapolis, October 2005

L. M. Zurk, M. R. Velankar, "Passive Sonar Array Sub-space Processing based on Modal Decomposition," IEEE Oceans, Washington DC, October 2005.

L. M. Zurk, "Performance of Mode-based Processing in Presence of Environmental Uncertainty," ASA, Vancouver, Canada, May 2005.

Northwest Electromagnetics & Acoustics Research Laboratory Dr. Lisa Zurk, Director http://nearlab.ece.pdx.edu/

NEAR-Lab

Acoustic source

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Bottom reverberation

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Incident acoustic wave

Specular reflection

Rough surface

Volume scattering

Layer scattering

Research Spotlight: Ocean Bottom ProfilingThere are a number of applications – such as marine habitat monitoring, mine detection, and Navy sonar operation - in which the profile of the ocean bottom is required. However, this information is generally difficult to obtain and prone to inaccuracy. One promising approach is to use a broadband sonar pulse (for example, a chirp signal) that can penetrate into the bottom, and then measure the time-frequency content of the reflected energy. Theoretically, this signal contains information on the acoustic properties of all the layers, but interpretation of this information is difficult due to scattering from ocean layers and buried inhomogeneities (for example, shells and rocks). Research in the Northwest Electromagnetics and Acoustics Research Laboratory (NEAR-Lab) is helping address this by developing acoustic scattering models, and validating these models with data from the Navy’s Shallow Water 2006 experiment. This is in collaboration with Applied Physics Laboratory, University of Washington and the Naval Research Laboratory (NRL).

The NEAR-Lab focus is on the modeling and analysis of electromagnetic and acoustic wave phenomenon for development of advanced signal processing techniques. The understanding of wave scattering provides a basis to devise and evaluate advanced signal processing algorithms for applications such as radar, sonar, and biomedical imaging.

NEAR-Lab Research involves numerical modeling, development of theory, and participation in large-scale collaborative experimentation efforts

Acoustics Research Projects:Acoustics Research Projects:• Physics-based processing for active sonar networksPhysics-based processing for active sonar networks• Acoustic propagation into ocean bottom sedimentsAcoustic propagation into ocean bottom sediments• Sonar mapping of coral reefs and fish aggregationSonar mapping of coral reefs and fish aggregation• Array processing of passive sonar systemsArray processing of passive sonar systems

Bathmetry map of Half Moon Caye, Belize, from sonar echo-sounding

data (collaboration with the Nature Conservancy)

Fish aggregation &

spawning

Echogram

Jorge on RV Knorr

Acoustic scattering can occur due to multiple phenomenon: specular reflection, rough surface scattering, volume scattering, and layer scattering.

The Navy-sponsored Shallow Water 2006 (SW06) experiment took place in August on the New Jersey shelf. PSU student Jorge Quijano participated in the experiment on the Research Vessel Knorr (owned by MIT Woods Hole) and in collaboration with APL/UW and NRL. Jorge was responsible for taking Conductivity- Temperature-Depth (CTD) measurements during the experiment, and will be using the chirp sonar data as part of his PhD dissertation.

Bottom layer 1Bottom layer 2

Bottom layer n

Chirp sonar from SW06 (courtesy of NRL)

Chirp sonar experiment

Data from Malta Plateau (Italy) showing observed striation patterns, and excellent agreement with NEAR-Lab model predictions.

Active sonar geometry, with normal mode propagation effects for acoustic energy