A COMPARISON OF SEVERAL SELF-STRUCTURING ANTENNA …

A COMPARISON OF SEVERAL SELF-STRUCTURING ANTENNATEMPLATES

B. T. Perry*, J.A. Nanzer J. E. Ross L.L. Nagyand E.J. Rothwell John Ross & Associates Delphi Research LabsECE Department 422 N. Chicago Street 51786 Shelby PkwyMichigan State University Salt Lake City, Utah Shelby Township, MIEast Lansing, MI 48824 [email protected]@egr.msu.edu

Successful operation of a self-structuring antenna (SSA) depends both on thelarge number of available antenna states, and the underlying characteristics of theantenna template. For example, if an antenna template is too small, an SSA likelywon’t perform well for low frequency applications, regardless of the switch states.Another possibility is that an SSA template is of appropriate size; in this case, theperformance of the antenna depends on both the switch states and theconfiguration of the antenna elements. Up to this point, the effect of theunderlying characteristics of the antenna template, i.e., the configuration of theantenna elements, has not been thoroughly studied. This paper looks tocharacterize the effect of the SSA template layout, using measured data such asstanding wave ratio (SWR), antenna patterns, and input impedance. By findingthe effect of template layout on the performance of the SSA, guidelines can becreated by which future layouts can be designed. Through this process, self-structuring antenna templates can be custom designed to better fit particularapplications.

This paper uses measured performance criteria to compare and contrast severalSSA template designs. These designs include a “standard”, linearly spaced SSAtemplate, as described in previous work, a variation based on a log-periodicdesign, and several templates that are fairly application specific. The applicationspecific templates are configured such that all switches and control hardware arealigned along one edge of the template. This allows the SSA to be used inapplications where the placement of both the feed network and the switches aredesired to be hidden away.

A COMPARISON OF SEVERAL SELF-STRUCTURING ANTENNATEMPLATES

B. T. Perry*, J.A. Nanzer J. E. Ross L.L. Nagyand E.J. Rothwell John Ross & Associates Delphi Research LabsECE Department 422 N. Chicago Street 51786 Shelby PkwyMichigan State University Salt Lake City, Utah Shelby Township, MIEast Lansing, MI 48824 [email protected]@egr.msu.edu

1. Commission and session topic: B1.1 Antenna Analysis and Design

2. Required presentation equipment: PowerPoint display

3. Corresponding author:Edward J. RothwellDepartment of Electrical and Computer EngineeringMichigan State UniversityEast Lansing, MI 48824Phone: 517-355-5231e-mail: [email protected]: 517-353-1980

6. New knowledge contributed by paper: This is the first comprehensivecomparison of differing self-structuring antenna template designs utilizing measureddata.

7. Relationship to previous work: Self-structuring antennas were introduced bythe authors at the 2000, 2001, and 2002 URSI National Radio Science Meetings.The basic operation and analysis of the antenna were described in these papers.

A Comparison of Several SSA Templates 1June 24, 2003

A Comparison of Several Self-StructuringAntenna Templates

URSI B Session 56Tuesday June 24, 8:20 am, Knox

MSU EM Group

B.T. Perry, J.A. Nanzer*, E.J. Rothwell, L.C. KempelMichigan State University

J.E. Ross, John Ross and AssociatesL.L. Nagy, Delphi Research Labs


Overview of Presentation

• Introduction to Self-Structuring Antennas (SSAs)• Description of templates• Measured SWR results• Measured pattern results• Conclusions


Self-Structuring AntennaConcept

• Self-Structuring Antenna system:

o Re-optimizes itself when its electromagnetic environment changes

o Arranges itself into a large number of possible antenna configurations

o Uses information from a receiver or sensor to determine fitness of eachconfiguration and determines future configurations

o Searches through possible configurations using binary search routine such as;Genetic algorithms (GAs)Simulated annealing (SA)Ant colony optimization (ACO)


Self-Structuring Antenna(SSA)


Self-Structuring AntennaTemplate

• A self-structuring antenna template iscomprised of a large number of wiresegments or patches interconnected bycontrollable switches

• For each configuration, the states of theswitches determine the electricalcharacteristics of the antenna

• For a template with n switches, there are2n possible configurations

• An asymmetric topology provides morediversity and less repeated states than asymmetric topology


Templates studied

• Four different templates were studied

o “Standard” templateo Log-periodic designo Edge-switch template 1o Edge-switch template 2

• Templates with switches located along the edge may prove moreuseful for automotive applications

• Templates with switches concentrated near the feed may be lessaffected by switch failures


Templates studied

• “Standard”template

• 32 switches =4.3 billioncombinations

• 16`` x 22``


Templates studied

• Log-periodictemplate

• 32 switches

• 16`` x 22``


Templates studied

• Edge-switchedType 1

• 32 switches

• 16`` x 22``


Templates studied

• Edge-switchedType 2

• 32 switches

• 16`` x 22``


SWR measurements

• Experimental setup

• Measure 30,000independent antennastates

• Look at statisticaldistribution of SWRvalues

• SWR calculatedrelative to 200ΩΩΩΩ


SWR measurements

1.0 2.0 3.01.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

SWR

0.01

0.1

1

10

100

0.020.030.040.050.07

0.20.30.40.50.7

23457

2030405070

% o

f sta

tes

at o

r bel

ow S

WR

error bars show 95% confidence interval

50 MHz

S

E1

E2L

Standard

Log-periodic


SWR measurements

1.0 2.0 3.01.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

SWR

0.01

0.1

1

10

100

0.020.030.040.050.07

0.20.30.40.50.7

23457

2030405070

% o

f sta

tes

at o

r bel

ow S

WR


100 MHz

SE1 E2

L

Edge 1

Edge 2


SWR measurements

1.0 2.0 3.01.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

SWR

0.01

0.1

1

10

100

0.020.030.040.050.07

0.20.30.40.50.7

23457

2030405070

% o

f sta

tes

at o

r bel

ow S

WR


150 MHz

S E1E2

L


SWR measurements

1.0 2.0 3.01.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

SWR

0.01

0.1

1

10

100

0.020.030.040.050.07

0.20.30.40.50.7

23457

2030405070

% o

f sta

tes

at o

r bel

ow S

WR


300 MHz

SE1

E2

L


SWR measurements

1.0 2.0 3.01.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

SWR

0.01

0.1

1

10

100

0.020.030.040.050.07

0.20.30.40.50.7

23457

2030405070

% o

f sta

tes

at o

r bel

ow S

WR


400 MHz

S

E1E2

L


SWR measurements

1.0 2.0 3.01.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

SWR

0.01

0.1

1

10

100

0.020.030.040.050.07

0.20.30.40.50.7

23457

2030405070

% o

f sta

tes

at o

r bel

ow S

WR


500 MHz

SE1

E2

L


SWR measurements

1.0 2.0 3.01.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

SWR

0.01

0.1

1

10

100

0.020.030.040.050.07

0.20.30.40.50.7

23457

2030405070

% o

f sta

tes

at o

r bel

ow S

WR


600 MHz

SE1E2

L

Standard

Log-periodic


SWR measurements

1.0 2.0 3.01.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

SWR

0.01

0.1

1

10

100

0.020.030.040.050.07

0.20.30.40.50.7

23457

2030405070

% o

f sta

tes

at o

r bel

ow S

WR


700 MHz

E1

E2

L

Edge 1

Edge 2


SWR measurements

1.0 2.0 3.01.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

SWR

0.01

0.1

1

10

100

0.020.030.040.050.060.08

0.20.30.40.50.60.8

234568

203040506080

% o

f sta

tes

at o

r bel

ow S

WR


800 MHz

E1

E2

L

Log-periodic


Pattern measurements

•Two types of measurements:

o Optimize at specific angle,then measure pattern withsettings fixedo Optimize at each angle

•Optimization:

o Standard GAo Population of 100o 10 generations followed

Control lines

PCMCIA DI/O

PCMCIA A/Dbalun

ANTENNATEMPLATE

SYNTHESIZED SOURCE

NOTEBOOKCOMPUTER

FIELD INTENSITY METER

receivedsignal strength

Input



o Reference angle setup (view looking down)

Transmittingantenna

SSA

Zero deg 90 deg

Front of SSA

Transmittingantenna

Front of SSA



Standard template 400 MHz vertical polarization

optimized at every angleoptimized at zero deg

0

90



Standard template 400 MHz horizontal polarization


0

90



Edge Type 1 template 400 MHz vertical polarization


0

90



Edge Type 1 template 400 MHz vertical polarization

optimized at 90 degoptimized at 180 degoptimized at 270 deg

0

90



Edge Type 1 template 400 MHz horizontal polarization


0

90



Edge Type 2 400 MHz vertical polarization


0

90



Edge Type 2 template 400 MHz horizontal polarization


0

90



Log-periodic 400 MHz vertical polarization


0

90



Log-periodic 400 MHz horizontal polarization


0

90


Conclusions

• SWRo Type 1 Edge-switched template has performance equal to

Standard designo Type 2 Edge-switched template has performance inferior to edge-

switched Type 1 design at most frequencieso Log-periodic design has poorer low-frequency performance, but

superior high-frequency performance

• Patternso All templates work well when optimized at all angleso Pattern can be steered to some extent by optimizing in a specific

direction

A COMPARISON OF SEVERAL SELF-STRUCTURING ANTENNA …

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