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Northwest Electromagnetics & Acoustics Research Laboratory
Dr. Lisa Zurk, Director
http://nearlab.ece.pdx.edu/
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
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
Comparison of NEAR-Lab rough
surface scattering codes
Comparison of Synthetic Aperture Radar
(SAR) image with optical image (SAR image
is from the MIT Lincoln Multi-mission ISR
Testbed, LiMIT)
Radar multipath modeling
(collaboration with MIT)
Direct
Target-Ground
eik ( 2 r  r )
r (r  r )
e ik ( 2 r )
r2
Ground-Target
ik ( 2 r  r )
e
r (r  r )
Ground-TargetGround
ik 2 ( r  r )
e
(r  r ) 2
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)
Research Spotlight: Terahertz Imaging
Until 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.
Selected NEAR-Lab Electromagnetics
Publications & Presentations:
HMX explosive granular structure
(image from LLNL UCRL-PRES150298)
Coupled grain scattering: random
media models (“Swiss cheese” model)
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)
Reference
SGPE (data)
LGPE (data)
SGPE (QCA)
LGPE (QCA)
2
Relative Spectral Level
10
1
10
0
10
0
2
4
6
Frequency (THz)
8
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.
10
NEAR-Lab Research involves numerical modeling, development of theory,
and participation in large-scale collaborative experimentation efforts
Northwest Electromagnetics & Acoustics Research Laboratory
Dr. Lisa Zurk, Director
http://nearlab.ece.pdx.edu/
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.
Fish
aggregation &
spawning
• Physics-based processing for active sonar networks
• Acoustic propagation into ocean bottom sediments
• Sonar mapping of coral reefs and fish aggregation
• Array processing of passive sonar systems
Acoustic
source
Target
Time/frequency spectra
Bottom
reverberation
Echogram
Data from Malta
Plateau (Italy)
showing observed
striation patterns,
and excellent
agreement with
NEAR-Lab model
predictions.
Spectrogram(Data)
-10
Spectrogram(Simulation)
-5
20
20
40
40
60
Time(min)
Active sonar geometry, with
normal mode propagation
effects for acoustic energy
Bathmetry map of Half Moon Caye,
Belize, from sonar echo-sounding
data (collaboration with the Nature
Conservancy)
-15
80
100
120
-10
40
60
80
80
-15
100
-20
Range vs time
20
60
dB
Acoustics Research Projects:
NEAR-Lab
100
120
120
-20
140
140
140
160
160
160
450 500 550
Frequency(Hz)
-25
450 500 550
Frequency(Hz)
-25
16 18 20 22 24 26
Range(km)
Research Spotlight: Ocean Bottom Profiling
There 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 timefrequency 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).
Incident acoustic
wave
Specular reflection
Rough surface
Acoustic scattering can occur due to
multiple phenomenon: specular
reflection, rough surface scattering,
volume scattering, and layer scattering.
c0 ,  0
c1 , 1
Volume scattering
Layer scattering
Chirp sonar
experiment
c2 ,  2
Bottom layer 1
Bottom layer 2
Bottom layer n
c3 ,  3
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.
0
Jorge on
RV Knorr
5
Depth(m)
10
15
20
25
30
Chirp sonar from SW06 (courtesy of NRL)
1000
2000
3000
Ping number
4000
5000
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.
NEAR-Lab Research involves numerical modeling, development of theory,
and participation in large-scale collaborative experimentation efforts