nsf sure program, summer 2002 / clemson university, clemson, sc 1 broadband arrays and switching...
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1NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
Broadband Arrays and Switching Antennas
Dan Palecek, SD School of Mines and Technology, Rapid City, SD
Dr. Anthony Martin, Clemson University, Clemson, SC
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Overview Background
Simulation SoftwareGenetic Algorithms5:1 Antenna System
Objectives and Strategies / ResultsBroadband ArraySwitching Antenna
Conclusions and Further Research
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Software Solves electric field integral equation
via method of momentsTraditional triangle basis functionsPulse test functions
Approximates geometry with straight wire segments
Utilizes genetic algorithm (GA) optimization
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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How Do GAs Work? Encode Parameters
Generate Initial Population
Evaluate and Assign Fitness Values
Select Parents Based on Fitness
Reproduce Through Recombination
Mutation
Chromosome
p1
{ { {p2 p3 p4
[ 0101 0011 1101 0101 ]{
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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5:1 Antenna System
L = 0.22 HR = 470
a = 0.4 mm
2a
L R
hL = 11.6 cm
h = 21.25 cm
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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5:1 Antenna System
Matching Network
Lm ZA
Transmission Line
Z0 = 50
1 : 4
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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5:1 Antenna System Bandwidth criteria
VSWR < 3.5 System gain > -4.0 dBi
2
1010log 1 90 dBisys eff AG M G
max
min
Bandwidthff
Cost Function - VSWR and Gain Penalty
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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5:1 Antenna System
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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5:1 Antenna System
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Broadband Array
ObjectiveDetermine if array retains broadband
characteristics
StrategyPlace 5:1 elements in array configurationVary spacing between elements and observe
effects
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Broadband Arrayh = 21.25 cm
hL = 11.6 cmd
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Broadband Array
Matching NetworkTransmission
Line
Z0 = 50
1 : 2
Lm
ZA
ZA
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Broadband Array
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Broadband Array
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Broadband Array200 MHz
300 MHz
400 MHz
500 MHz
600 MHz
700 MHz
800 MHz
900 MHz
1000 MHz
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Switched Antenna
ObjectiveExtend bandwidth of 5:1 antenna via
switching
StrategySwitch in various loaded wire segmentsOptimize for lower frequency bandOpen switch, examine effects on 5:1 band
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Switching Antenna
Switch Open for 5:1 Band
Loaded Segment
5:1 Antenna
Switch
Switch Closed for New Band
Loaded Segment
5:1 Antenna
Switch
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Switching Antenna
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Switching Antenna
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Conclusions
Broadband ArrayBroadband performance can be
maintained
Switching AntennaBandwidth can be increased
NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC
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Further Research
Broadband Array Feedline between matching network and array
elements Matching network
Switching Antenna Switching mechanism Software modifications