Presentation Loui

8/3/2019 Presentation Loui

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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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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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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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IN BAND

Out of BAND

Bi-static scattering of out-of-band signals


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Angle response requires unit-cell modification


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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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TE/TM transmittance through tapered-hole array

Tapered

0.7


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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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Numerical discovery of anomalous transmission


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Changing the length and permittivity in one slot


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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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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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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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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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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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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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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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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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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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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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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 -

-

Org. 1652 Plasma Physics -- Org. 1727 Applied Photonics -

Truman Committee!

DMTS: Billy C. Brock

Mentor Manager

Kurt W. Sorensen

Presentation Loui

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