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LDRD Day, 2008LDRD Day, 2008
Jacques H. Loui
Passive & Active Electromagnetic Frequency
Selective Surfaces for High-Power Beam
Applications
Org: 05345 SAR Sensors & Technologies
LDRD Investment Area: Strategic Partnerships
TRUMAN FELLOWSHIP2006-2009
DMTS: Billy C. Brock
Mentor Manager
Kurt W. Sorensen
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LDRD Day, 2008LDRD Day, 2008
Goal, Approach and Content
Goal:Produce novel, reconfigurable, metal/dielectric surfaces/volumes for adaptive control over EM scattering.
Approach:Embed tunable materials as periodic unit-cells in a thick metal plate to affect electromagnetic wave
propagation based on electrical configuration.
Variation of unit-cell geometry
Controls Frequency & Angle Dependence
Variation of unit-cell filling
Addresses Tunability
tapered unit-cells
compound unit-cells
sub-wavelength unit-cells anomalous transmission
changing permittivity
permeability tensors
ferrite-based FSSs dispersion engineering
EM Applications
Radome/Filters
Flat Lens
Tunable Absorbers
Meta-Surfaces
Theoretical Numerical Experimental ApplicationContent:Progress made in areas
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LDRD Day, 2008LDRD Day, 2008
Approach for tunable FSSs
Perforated Thick Metal Plate
Natural Heat Sink, Compact and Rigid
amplifiers
attenuator
feed
diode
switches
delay
Shutters
Flat Lens
Absorbers
Power Combiner
Antenna Arrays
Mixers/Sensors
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LDRD Day, 2008LDRD Day, 2008
IN BAND
Out of BAND
Bi-static scattering of out-of-band signals
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LDRD Day, 2008LDRD Day, 2008
Angle response requires unit-cell modification
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LDRD Day, 2008LDRD Day, 2008
Phase criterion determines resonancelocation
determines Q of the resonanceand is dependent on the diameter/periodratio, larger d/p leads to broadbandresponse
Angle response can be improved via hole taper
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LDRD Day, 2008LDRD Day, 2008TRUMAN FELLOWSHIP
2006-2009
L
incr
r
Parab
olaAx
is
New ParabolicTaper
h
01-16-2007
Parabolic taper allows more rays to pass
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LDRD Day, 2008LDRD Day, 2008
TE/TM transmittance through tapered-hole array
Tapered
0.7
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LDRD Day, 2008LDRD Day, 2008
New Contribution (CompoundUnit Cell)
z
x
y
x
y
DielectricLayersorMetalShort
Metal
Current State of the Art(Simple Unit Cell)
z
x
y
x
y
Metal
DielectricLayersorMetal
Short
Introduction to compound unit cell
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LDRD Day, 2008LDRD Day, 2008
Numerical discovery of anomalous transmission
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LDRD Day, 2008LDRD Day, 2008
Changing the length and permittivity in one slot
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LDRD Day, 2008LDRD Day, 2008
Photographed by: Daryl Reckaway
Stress relief by oven curing isnecessary before Wire EDM
Oxidation in small holesprevents electrical discharge
3-hrs of machine time per slit
Wire
Hole
Org. 024312 Project Machining & Rapid Turn
Photographed by: Daryl Reckaway
CNC Wire Electrical Discharge Machining
Clarence D. Esquibel
Experimental work on compound FSS
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LDRD Day, 2008LDRD Day, 2008
Construction of a FSS measurement apparatus
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LDRD Day, 2008LDRD Day, 2008280mm f-1 Hyperbolic Lens and its holder
In-house microwave aspheric lens design code
MATLAB code
3D skew ray
Aspheric lenses
Dynamic movement
Spot diagrams
Beam tracing*
* Work in progress
K-Band
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LDRD Day, 2008LDRD Day, 2008
Magnetically biased ferrite can provide tunability
Enables active amplitude, phase andpolarization control
+
+= y
Ejx
Ey
Ejx
ExE
yxyx
x
2
2
2
2
Current controls magnetic bias H0
H0 changes permeability tensor
which affects propagation constant
There are two models for
the permeability tensor:
1. Fully saturated based onphysical arguments.
2. Partially saturated based onempirical data.
3. Problem: they dont agree
Fullysaturated
case
Partiallysaturated
case
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LDRD Day, 2008LDRD Day, 2008
gyrotropic
bias (precession frequency)
saturation magnetization
gyro-magnetic ratio
0 5 10 15 20
-25
-20
-15
-10
-5
0
5
10
15
20
25
Frequency (GHz)
eff
+eff
-eff
Circular polarized wave propagation
(Infinite Ferrite medium)
Saturated Ferrite under bias
Notice that
in this region
Tunability in infinite ferrite medium (Saturated)
0 5 10 15 20
-50
0
50
100
150
200
Frequency (GHz)
phase()and/rotation()(deg/mm)
(H=[0.8 1 1.2]H0)
(H=[0.8 1 1.2]H0)
Phase
Rotation
It would be reallynice if we had
in the sameregion for now
we haveattenuation
TunableDelay
10 GHz 3570 G
3.57 T100 GHz
1 THz 35.7 T
357 T30m
3.57 KT3m
Frequency range limitedby available magnet
Tunable Absorption
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LDRD Day, 2008LDRD Day, 2008
0 5 10 15 20-40
-20
0
20
40
60
80
100
120
140
160
Frequency (GHz)
phase()and/rota
tion()(deg/mm)
(++
-)/2 (Saturated)
(+-
-)/2 (Saturated)
(M=[0 0.5 0.9]Ms)
(M=[0 0.5 0.9]Ms)As M from 0 Ms, the
partially saturated
tensor model (green &pink) and the fully
saturated tensor model(red and blue) do not
connect!
Phase
Rotation
Saturated Ferrite under bias
gyrotropic
bias (precession frequency)
saturation magnetization
Circular polarized wave propagation
10% Error [Rado, 1953]
[Green&San
dy,1974]
Partially Saturated Ferrite under bias
Curved fitted with no physical bases(Infinite Ferrite medium)
0 5 10 15 20-2
-1
0
1
2
3
4
5
Frequency (GHz)
eff
+'eff
(Saturated)
-'eff
(Saturated)
+'eff
(M=[0 0.5 0.9]Ms)
-'eff
(M=[0 0.5 0.9]Ms)
Low
FieldL
osses
Infinite ferrite medium (Partially Saturated)
Wave plateTunableRotation
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LDRD Day, 2008LDRD Day, 2008
Graduate StudentTexas A&M
Jacob J. McDonald
Mentor DMTS
Billy C. Brock
Truman Fellow
Jacques H. Loui
EE ProfessorCU Boulder
Edward F. Kuester
Measuring the tensor permeability of ferrites
15 15.5 16 16.5 17 17.5 18 18.560
80
100
120
140
160
180
200
220
240
Frequency (GHz)
(1/m)
Empty Waveguide
Bias=0.00V
Bias=0.03V
Bias=0.06V
Freq: Ku-Band
Measures permeabilitytensor of partial & saturatedcylindrical ferrite samples
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LDRD Day, 2008LDRD Day, 2008
How do we put ferrite inside the unit-cells?
General Solution
4th order PDE
Parameter of Interest
waveguide filling
parameter of interestSpecific solutions only possiblefor simple structures
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LDRD Day, 2008LDRD Day, 2008
Node-Based Eigen Mode Solver Homogeneous (Scalar)Edge-Based Eigen Mode Solver Inhomogeneous [Tensor]
+ +
Development of a high-order 2D Eigen-solver
http://www.washington.edu/ -
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LDRD Day, 2008LDRD Day, 2008
Active Ferrite-based FSS Concept
Fields of research involved:
Tunable materials [dispersive tensor]
Electromagnetic scattering
Periodic structures
In homogeneously filled waveguides
Dispersion engineering
Material measurement capabilities
Quasi-optic measurement techniques
TRUMAN FELLOWSHIP2006-2009
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LDRD Day, 2008LDRD Day, 2008
Summary & Conclusions
Accomplishments:
Theoretical:
Explained the origin of anomalous transmission
Showed via net-work theory the mechanism that
governs scattering from thick FSSsNumerical:
MM-EGSM method for analyzing anomalous andextraordinary transmission problems
High-Order 2D FEM Eigen mode solver
3D skew ray tracing lens design software
CST script for design corrugate horns
Experimental:
Gaussian beam measurement system
Ferrite tensor characterization system
Application:
Ferrite based thick-metal FSSs for radomeapplications
Ferrite based devices for beam steering (SARrelated)
Significance:
1. This work satisfies the strategic intent of the Truman
fellowship.
[multiple orgs., 3 universities, 2 graduate students,6+ publications (one in physical review, 3 journal,3 conference), 3 TAs, 4+ Sand Reports, 1additional LDRD for SAR, and supported theefforts of GC-LDRD in meta-materials]
2. Provided Sandia a firm footing (tools & infrastructure) inthe area of sub-wavelength EM scattering and RF ferritebased innovations.
3. Multi-morphic surfaces open new venues for low-observables and benefits both Strategic Partnership andDefense Assessment Investment Areas.
Goal:Produce novel, reconfigurable, metal/dielectric surfaces/volumesfor adaptive control over EM scattering.
Approach:Embed tunable materials into the periodic unit-cells of a thick
metal plate to affect electromagnetic wave propagation based onelectrical configuration.
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LDRD Day, 2008LDRD Day, 2008
Utilization of laboratory resources & thank you!
Don Davis Org: 02455Adrian L. Casias Org: 02452
2500W CO2 Laser
Nick Lopez Org: 05343
Bart D. Chavez Org: 02455
- Mentor -Billy Brock- Manager -
Kurt W. Sorensen-
Org. 5345 SAR Sensors -
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Org. 1652 Plasma Physics -- Org. 1727 Applied Photonics -
Truman Committee!
DMTS: Billy C. Brock
Mentor Manager
Kurt W. Sorensen