Post on 21-Jan-2016
ONR AppEl @ 1
0 0.1 0.2 0.3 0.4-0.4
-0.2
0
0.2
0.4
Time /Sec
A Wave Chaos Approach to Understanding and
Mitigating Directed Energy Effects
Steven Anlage, Thomas Antonsen,Edward Ott
T1
T2
0 0.2 0.4 0.6 0.8 10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0.5
1
1.5
2
2.5
3
3.5
3 3.002 3.004 3.006 3.008-0.2
0
0.2
Time /Sec
Vo
lts
ONR AppEl @ 2
The Maryland Wave Chaos Group
Tom Antonsen Steve AnlageEd Ott
Jen-Hao Yeh James HartNow at Lincoln Labs
Biniyam Taddese
Graduate StudentsMing-Jer LeeHarita TennetiTrystan Koch
Undergraduate StudentChristopher Bennett
Post-DocDr. Gabriele Gradoni2010 URSI Young Scientist Award
NRL Collaborators: Tim Andreadis, Lou Pecora, Hai Tran, Sun Hong, Zach Drikas, Jesus Gil Gil
Funding: AFOSR MURI 2001; AFOSR; ONR MURI 2007; ONR AppEl
ONR AppEl @ 3
A Wave Chaos approach to understanding / quantifying DE Effects in electronics
The model works for ‘ray-chaotic’ enclosures
Two incident rays with slightly different initial directions have rapidly diverging trajectories
Embrace CHAOS as the central organizing principle!
Many electronic enclosures display ray chaos
Computer enclosuresAircraft cockpitsShip compartmentsOfficesetc.
ONR AppEl @ 4
The Random Coupling Model
A quantitative model of statistical and systematic aspects of HPM effects in enclosures
Statistical aspects:
The underlying classical chaos means that the waveproperties are ‘universal’ and governed by Random Matrix Theory (RMT)
► The statistics of all wave properties (resonant freqs.,standing wave patterns, Z, Y, S, etc.) are UNIVERSALand governed by a single loss parameter:
spacing
dB
f
f
3
0.0 0.5 1.0 1.50
1
2
VoltsV || 2
|)(| 2VP
Experimental Data
Terrapin Terrapin AlgorithmAlgorithm
0.0 0.5 1.0 1.50
1
2
VoltsV || 2
|)(| 2VP
Experimental Data
Terrapin Terrapin AlgorithmAlgorithm
The non-universal aspects are captured bythe radiation impedance Zrad of the coupling ‘ports’
Zrad of the ports can be determined by a numberof techniques, both experimental and theoretical
RCM Web Site: http://www.cnam.umd.edu/anlage/RCM/index.htm
ONR AppEl @ 5
Effect of Direct Ray Paths
Original Random Coupling Model (RCM) - RF energy is randomized on entering cavity - Only radiation impedance of ports, cavity volume and average Q are important
In some geometries, or in narrow frequency bands specifics of internal geometry are important
Modified Random Coupling Model - J. Hart et al., PHYSICAL REVIEW E 80, 041109 (2009) - Allows for systematic improvement by inclusion of geometric details if known - Can be used in conjunction with measured data
Systematic aspects of HPM EffectsInclusion of ‘Short Orbits’ in the RCM
ONR AppEl @ 6
Extensions of The Random Coupling Model
Systematic aspects of HPM EffectsInclusion of ‘Short Orbits’ in the RCM
James Hart, T. Antonsen, E. Ott, Phys. Rev. E 80, 041109 (2009)
2/12/1avgavgavg RiRXiZ�����
is a complex matrix withuniversal fluctuations governedby the loss parameter f3dB/f↔ ↔ ↔
↔
↔
↔ ↔ ↔↔
↔ ↔ ↔↔
↔
Survival probability in the ensemble Uniform attenuation
)/(Ak
Theory work funded by AFOSR
ONR AppEl @ 7
Data and Theory smoothedwith the same 125-cm
(240 MHz window) low-pass filter
Nonuniversal Properties Captured by the Extended RCMEmpty Cavity Data
Theory includes all orbits to 200 cm length
6.0 6.5 7.0 7.5 8.0
0
20
40
60
80R
esis
tanc
e (
)
Frequency (GHz)
Re[Z11
]
Re[Z(L)
11]
Re[ZR,11
]
6.0 6.5 7.0 7.5 8.0
-40
-20
0
20
40
Rea
ctan
ce ()
Frequency (GHz)
Im[Z11
]
Im[Z(L)
11]
Im[ZR,11
]
6.0 6.5 7.0 7.5 8.0
-40
-20
0
20
40
-40
-20
0
20
40
R
eact
ance
()
Smoothed Im[Z11
]
Smoothed Im[Z(L)
11]
Im[ZR,11
]
Res
ista
nce
()
Frequency (GHz)
Smoothed Re[Z11
]
Smoothed Re[Z(L)
11]
Re[ZR,11
]
J.-H. Yeh, et al., Phys. Rev. E 81, 025201(R) (2010); J.-H. Yeh, et al., arXiv:1006.3040
Experimental work funded by AFOSR,
and now ONR/AppEl
ONR AppEl @ 8
Extensions of The Random Coupling Model
Realistic systems consist of many coupled enclosuresCan the RCM be extended to handle these situations?
J. P. Parmentier (ONERA)
ONR AppEl @ 9
Extending the RCM to the case of Coupled Cavities
The statistics of coupling are dominated by the statistics of transmission through the first cavity,scaled by the mean impedance of the next cavity
Generalize to an arbitrary cascade of enclosuresand treat junction topology
11
21
I
VZc
Fluctuations in transmissionthrough cavity 1
Mean properties of cavity 2
Cavity 1 Cavity 2
Approximations:high loss, weaktransmission
ONR AppEl @ 10
Extending the RCM to the case of Coupled Cavities
Future Work:
Consider networks of coupled cavitiesGraph topology
ONR AppEl @ 11
The Statistics of Tunneling between Enclosures
In some cases, two enclosures will be coupled by structures beyond cutoff
Examples include metal ducts at frequencies below cutoff,intermediate rooms/compartments that are below resonance
Can we use what we know about chaotic eigenfunctions to solve this problem?Does it make a difference if the enclosures are regular or chaotic?
Enclosure 1 Enclosure 2
Bar
rier
Work in collaboration with Lou Pecora @ NRL
Enclosure 1 Enclosure 2
Barrier
Regular Enclosure caseRay Chaotic Enclosure case
ONR AppEl @ 12
The Statistics of Tunneling between Enclosures: The 1D Case
Energy splitting k2 is proportional to the tunneling rate through the barrier
ck
ONR AppEl @ 13
Splitting Fluctuations versus Energy
These splittings, and their fluctuations, are predictable in the chaotic case
Numerical simulationsby Lou Pecora (NRL)
ONR AppEl @ 14
Results of Wave Chaos Theory
The theory uses the random plane wave hypothesis to calculate the tunneling rate
Sliding average of mean splitting Sliding average of splitting fluctuations
Black lines (Data) – simulations by Lou Pecora (NRL)
Surprisingly, all threeagree quite closely…
Wave chaos theory in agreement with simulations
ONR AppEl @ 15
Ray-ChaoticEnclosure
Barrier
InfiniteWaveguide
The tunneling escape rate will vary from mode to mode, giving fluctuationsin the quality factor of the modes.
The mean and fluctuations of the 1/Q with k2 should follow the wave chaos theory predictions
An Experiment to Test the Wave Chaos Tunneling Theory
ONR AppEl @ 16
New Research and Transfer of RCM Knowledge Base to Naval Research Lab
We are collaborating with the group of Tim Andreadis to test the RCM is more realisticscenarios, and to transfer our knowledge / know-how to DoD
Experimental tests of the RCM in 3D enclosuresHai Tran and Zach Drikas
Radiation Impedance Measurement New Antenna Configuration
ONR AppEl @ 17
Anlage et al. Acta Physica Polonica A 112, 569 (2007)
The Electromagnetic Chaotic Time-Reversal Sensor
60ns pulse with 7GHz (λ~4cm) center frequency.
Transmitted Sona
Work funded by ONR MURI 2007
ONR AppEl @ 18
ELECTROMAGNETIC Chaotic Time-Reversal Sensor:- Injection of time reversed Sona
Sensors based on time-reversed pulse reconstruction:B. T. Taddese, et al., Appl. Phys. Lett. 95, 114103 (2009) B. T. Taddese, et al., arXiv:1008.2409
ONR AppEl @ 19
Short Monopole Inside
Electromagnetic Time-Reversal of Enclosure with ApertureSun Hong, Zach Drikas, Hai Tran, Jesus Gil Gil, Tim Andreadis, NRL
( )ix t
( )y t
( )rx t
Step 1:
1
2
Port 1
Port 2
400 420 440 460
-4
-2
0
2
4
6x 10
-5
time (ns)
Am
plitu
de
ci(t)*h(t)
5ns
ONR AppEl @ 20
Conclusions
The Random Coupling Model is being extended and generalized in new waysShort OrbitsConnected EnclosuresElectrically Large Antennas
Theory and Experiment work in parallel, and stimulate each other
NRL Collaboration has resulted in:New experiments and new applications for the RCM and time-reversed EMExtension of the RCMTransfer of know-how to DoD
IC Post-Doc grant: Nonlinear time-reversed electromagneticsDURIP proposal: System for Investigation of Terahertz Wave Chaos
Future Work:Experimental test of tunneling fluctuationsTheory of multiple connected and networked enclosuresModeling and experiments of fading statistics