2790 Indian Ripple Road • Russ Research Center • Dayton, Ohio • 45440

(937) 320-5999 • (937) 320-7773 • sstarr@spectra-research.com • www.spectra-research.com

Proprietary Proprietary -- Competition SensitiveCompetition Sensitive

Fragmented Volume AntennasFragmented Volume AntennasTechnology OverviewTechnology Overview

SBIR RFI – AF071-357Presented to:Larry LeDuc

Larry.Leduc@edwards.af.mil661.277.8628

Presented by:Daniel D. Reuster, Ph.D

& Jeff Woolsondreuster@spectra-research.com

937.320.5999x28

30 November 2006

30NOV06

Page 2 of 29

PROPRIETARY

OverviewOverview

• Small, woman-owned business founded in 1989• Staff of multi-disciplined engineers and scientists• Wide array of technology thrusts

– Advanced antennas, RFID, EO/IR, and software modeling/simulation

• Over 100 development programs – 7 US patents• Various EM Numerical Analysis / CAD Packages• Rapid Prototyping Capability (PCB, plastic, light metals)

PROPRIETARY 30OCT06

Ongoing ProgramsOngoing ProgramsRadio Frequency Identification (RFID)Radio Frequency Identification (RFID)

• Combat Identification Tags

- Air-to-Ground CID

- Ground-to-Ground CID

- X, Ku, Ka bands

• Asset Tracking

Advanced AntennasAdvanced Antennas• Miniaturized GPS

• Multi-band ESM

• Electronically scanned arrays

• Non-invasive medical imaging

X-band layer

Ku-band layerKa-band layer

EO / IR Technologies EO / IR Technologies • Non-intrusive traffic monitoring

• Pavement profiler

• Flash Ladar Processing

• Laser threat warning system

• IED detection system

• CW Laser identification system

Advanced Training SystemsAdvanced Training Systems• Non-pyrotechnic Cueing Device

CEM Modeling / Rapid PrototypingCEM Modeling / Rapid Prototyping• IV & V• CAD / CAM / Solid modeling

30NOV06

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PROPRIETARY

Fragmented Aperture Tech.Fragmented Aperture Tech.

10” x 10” Antenna Broadside Radiation

• Gain > 5 dB over the frequency range of optimization• Good agreement with experimental measurements• This design has ~3 dB more gain than Archimedean spiral

Feed

0 1 2 3 4

Bro

adsi

de G

ain,

dB

-5

0

5

10

15FDTD ModelMeasuredAperture Gain Spiral Antenna

OptimizationRange

Optimized 0.8 - 2.5 GHz

30NOV06

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PROPRIETARY

Fragmented Aperture Cont.Fragmented Aperture Cont.

Choose aperture

basis

Create initial population of

antennasEvaluate and rank

each antenna design

Rank based on pre-defined criteria (e.g. realized gain)(2), (3)

Create next generation of candidates

Success!-30

-25

-20

-15

-10

-5

0

5

10

105321.5.3

Rea

lized

Gai

n (d

B)

Frequency (GHz)

Area GainFar Field V-Pol

Anech. Chmbr H-PolAnech. Chmbr V-pol

Compact RangeNumerical Prediction

Goal met?

Successful design requires(1) Wise choice of aperture basis - brute force doesn’t

work – no convergence(2) Fast, accurate computation engine (UWAA-funded

software enhancements); 100’s of parallel cpu’s (3) Careful definition of optimizer cost function

Successful design requires(1) Wise choice of aperture basis - brute force doesn’t

work – no convergence(2) Fast, accurate computation engine (UWAA-funded

software enhancements); 100’s of parallel cpu’s (3) Careful definition of optimizer cost function

Beowulf Clusters

GTRI Patent (US# 6,323,809 )

Choose wisely – use antenna insights (1)

Generate 100’s of random candidates

Use genetic algorithm to create (better) antennas

30NOV06

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PROPRIETARY

GPS Antenna ExampleGPS Antenna Example

• Element designed with a “wideband feed”

• This results in more bandwidth for a given element sizeWideband feed

30NOV06

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PROPRIETARY

Numerical and Virtual ModelingNumerical and Virtual Modeling

From Numerical Modeling

Direct to CAM Machining

30NOV06

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PROPRIETARY

Fabricated Fabricated -- 2 inch Element2 inch Element

Frequency (GHz)

S11 (dB)

PredictedMeasured

S11 Comparison

30NOV06

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PROPRIETARY

MetaMeta--MaterialMaterial

• ARLON AD600 Commercial Meta-Material– DK 6.3-j0.4: 0.125” thickness: 1oz Cu

30NOV06

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PROPRIETARY

ApproachApproach

• Utilize 3D FragmentedAperture Antennas– Fragmented apertures

antennas were developed to best utilize available planar area

– 3D fragmented apertures(fragment volumes) bestutilize available volume

30NOV06

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PROPRIETARY

Exploratory GeometryExploratory Geometry

50 ohmCoax Feed

10” x10” x 10”quadrant

Symmetricalremainingquadrants

GroundPlane

y

z

30NOV06

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PROPRIETARY

Exploratory GeometryExploratory Geometry

• 3D AutocadDXF view of representative quadrant

• Ground plane is not shown

• Symmetrical quadrants not shown

10x10x10 Quadrant

¼ of antenna shown (two planes of symmetry)Monopole

Feed (50ohm)

1 inch wiresegments

30NOV06

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PROPRIETARY

Case 5: 100Case 5: 100--400 MHz400 MHz

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1

frequency (GHz)

refle

ctio

n co

ef (m

ag)

case5: 10x10x10, 1 inch wire, 100-400 MHz

0 0.1 0.2 0.3 0.4 0.5-10

-5

0

5

10

frequency (GHz)

real

ized

gai

n (d

BiL

)

case5: 10x10x10, 1 inch wire, 100-400 MHz

• 4:1 bandwidth achievable • Electrical size of antenna at upper end of band can cause pattern changes

30NOV06

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PROPRIETARY

Use of Lumped ElementsUse of Lumped Elements

Conventional Matching Network: Embedded Lumped Elements:

• Lumped elements placed before feeds point can only adjust match

• Pattern fixed, i.e. determined by placement of wires

3D FragmentedAntenna R,L,C

R,L,C GroundPlane

Feed Pt

3D FragmentedAntenna

Feed Pt

GroundPlane

• Lumped elements now change both the match and the radiation pattern

• Could have reconfigurable performance with tunable components

• Fabrication issues

30NOV06

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PROPRIETARY

Use of Lumped Elements (Cont)Use of Lumped Elements (Cont)

Multiple ports: Multiple ports, multiple functions

• Lumped elements placed on secondary feed points change both the match and radiation pattern

• Easy to fabricate (wires all metal)• Potentially easier to tune

components if reconfigurable desired

3D FragmentedAntenna

GroundPlane

Feed Pt

3D FragmentedAntenna

GroundPlane

Feed Pt

R,L,CFilter1 Filter2

• Each port supports separate function

• RF filters achieve band splitting and secondary port reactance for matching

• Extendable beyond two ports

30NOV06

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PROPRIETARY

Reduced, TwoReduced, Two--Port GeometryPort Geometry

• Reduce volume of antenna by 50%

• Add second port

• Initially consider loaded port 2 configurationsPort 1: 50 ohm

Coax Feed

10x10x10quadrant

Symmetricalabout

GroundPlane

Port 2: 50 ohmCoax Feed

y

z

30NOV06

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PROPRIETARY

Case 6: TwoCase 6: Two--Port, 100Port, 100--400 MHz400 MHz

0 0.1 0.2 0.3 0.4 0.5-10

-5

0

5

10

frequency (GHz)re

aliz

ed g

ain

(dB

iL)

case6: 10x10x10, 1 inch wire, 100-400 MHz

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1

frequency (GHz)

refle

ctio

n co

ef (m

ag)

case6: 10x10x10, 1 inch wire, 100-400 MHz

• 4:1 bandwidth achievable, Nice gain across band• Second port offsets size reduction

30NOV06

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PROPRIETARY

Reactive MultiReactive Multi--port demonstrationport demonstration

• Reduced volume of antenna by total of 80% from initial size

• Second port now reactive termination

Port 1: 50 ohmCoax Feed

6x8x8quadrant

Symmetricalabout

GroundPlane

Port 2: 50 ohmCoax Feed

y

z

30NOV06

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PROPRIETARY

Reactive MultiReactive Multi--port Demonstrationport Demonstration

• Multi-purpose port– 100-400 MHz

• VSWR better than 1.5 across majority of this band

• Demonstration that reactive matching of 2nd

port in combination with 3D fragmented design can lead to significant volume reduction

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1

frequency (GHz)

refle

ctio

n co

ef (m

agni

tude

)

30NOV06

Page 20 of 29

PROPRIETARY

3D Fragmented Antenna Fabrication Process3D Fragmented Antenna Fabrication Process

Use stereo-lithography (SLA)and/or selective lasersintering (SLS) Machinesto make 3D part

Experimental workHas consideredvarious coating options

Optional insertion of high index materials(e.g. dielectrics) intokey areas of 3D structure

Significant weight savings

Final part includes3D antenna structureand placed highindex materials

30NOV06

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PROPRIETARY

MultiMulti--Purpose Antenna Purpose Antenna VV--PolPol OmniOmni--Directional Antenna (30Directional Antenna (30--450 MHz)450 MHz)

x

z

y8”

2”

4”

16”

9”

1”

Female N-FeedConnector

1 inch “Fragmented”Wire Mesh Structure

• 4” x 16” x 9” antenna structure

• Two degrees of symmetry– xz plane– yz plane

• Single Female N-Feed connector

• Dk=10 ceramic volume• 3D “Fragmented” wire

mesh design

30NOV06

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PROPRIETARY

Mesh DesignMesh Design

• Within each of the four symmetric regions, a wire mesh structure is generated using a genetic algorithm.

• The wire directions are constrained to the x, y and z axes.

x

z

y8”

2”

4”

16”

9”

Female N-FeedConnector

1 inch “Fragmented”Wire Mesh Structure

30NOV06

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PROPRIETARY

Genetic CodeGenetic Code

• Each cell contains three wire segments– x, y, z

• They are represented by a 3-bit binary number

• The binary numbers are concatenated together to form the genetic code for the antenna– 111011101110100010000001

x

y

z111

x

y

z011

x

y

z101

x

y

z110

x

y

z100

x

y

z010

x

y

z001

x

y

z000

30NOV06

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PROPRIETARY Sub MaskingSub MaskingBoundary Condition ImplementationBoundary Condition Implementation

x

y

y-face boundary condition 101

upper boundary condition 110lower boundary condition 001 x-face boundary condition 011

corner boundary condition 001

• The antenna design volume is terminated by five boundary regions:– upper, lower, x-face, y-face & corner

• These boundary conditions are logical “ANDed”to the genetic code to provide a smooth boundary.

Page 25 of 29

PROPRIETARY

Design FabricationDesign Fabrication

The antenna consists of a dielectric core 16”x 9”x 4” inter-woven with a fragmented conductive lattice covered with a Radome of ¼” thickness attached to an 18”x 6” mounting plate using nylon screws.

Unit Weight1. Dielectric Assembly = 46 to 52 lbs.2. Aluminum mounting base = 2 lbs.

10 oz.3. Radome material = 4.1 oz.4. Total unit weight ~ 55 lbs.

The unit provides mounting holes in each corner capable of accommodating a 1/4” screw/bolt.

Page 26 of 29

PROPRIETARY

Fabrication (Cont.)Fabrication (Cont.)

Once an antenna design has been finalized it will be converted into a 3-D model using AutoCAD.

The dielectric substrate will be fabricated using 8 segments of 8”x9”x1” C-STOCK ceramic filled plastic.

Clearance for the conductive lattice will be cut into each individual piece using a 3-D milling machine.

Page 27 of 29

PROPRIETARY

Fabrication (3)Fabrication (3)

Once all pieces are cut, the two pieces that make up the first layer will be bonded together (Step 1). The conductive lattice will then be build-up using 3/16” brass tubing soldered together at all joints (Step 2).

Page 28 of 29

PROPRIETARY

Fabrication (4)Fabrication (4)This process will continue with the completion of each layer of lattice until the entire stack is complete.

The finished block will then be attached to the mounting plate via a total of sixty-four nylon screws

An ‘N’ Panel Receptacle Jack will then be mounted to the bottom of the mounting plate.

A Radome will then be constructed using C-FOAM adhesive-backed low-loss polyethylene foam.

30NOV06

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PROPRIETARY

AF071AF071--357 Requirements357 Requirements

• 100-300 MHz Frequency Band• 20 dBi Antenna Gain / 30 deg. Beam Width• 10’ x 10’ x 10’ Volume Constraint• 300 lbs Weight Requirement• Dual Feed V-Pol and H-Pol• Mount on EX105/10-2.3 from Mastsystems• VSWR < 2 (1.5 if possible)• Traditional Antenna Design would require

40’ x 40’ x 40’ Volume Constraint