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Broadband Arrays and Switching Antennas. Dan Palecek , SD School of Mines and Technology, Rapid City, SD Dr. Anthony Martin , Clemson University, Clemson, SC. Overview. Background Simulation Software Genetic Algorithms 5:1 Antenna System Objectives and Strategies / Results

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Broadband Arrays and Switching Antennas

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Broadband Arrays and Switching Antennas

Dan Palecek, SD School of Mines and Technology, Rapid City, SD

Dr. Anthony Martin, Clemson University, Clemson, SC


Overview

  • Background

    • Simulation Software

    • Genetic Algorithms

    • 5:1 Antenna System

  • Objectives and Strategies / Results

    • Broadband Array

    • Switching Antenna

  • Conclusions and Further Research

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Software

  • Solves electric field integral equation via method of moments

    • Traditional triangle basis functions

    • Pulse test functions

  • Approximates geometry with straight wire segments

  • Utilizes genetic algorithm (GA) optimization

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


How Do GAs Work?

Encode Parameters

Chromosome

[ 0101 0011 1101 0101 ]

{

{

{

{

Generate Initial Population

p1

p2

p3

p4

Evaluate and Assign Fitness Values

Mutation

Select Parents Based on Fitness

Reproduce Through Recombination

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


5:1 Antenna System

h = 21.25 cm

L

R

2a

hL = 11.6 cm

L = 0.22 mH

a = 0.4 mm

R = 470 W

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


5:1 Antenna System

Matching Network

TransmissionLine

1 : 4

Z0 = 50 W

Lm

ZA

G

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


5:1 Antenna System

  • Bandwidth criteria

    • VSWR < 3.5

    • System gain > -4.0 dBi

  • Cost Function - VSWR and Gain Penalty

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


5:1 Antenna System

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


5:1 Antenna System

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Broadband Array

  • Objective

    • Determine if array retains broadband characteristics

  • Strategy

    • Place 5:1 elements in array configuration

    • Vary spacing between elements and observe effects

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Broadband Array

h = 21.25 cm

hL = 11.6 cm

d

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Broadband Array

Matching Network

TransmissionLine

ZA

1 : 2

Z0 = 50 W

Lm

ZA

G

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Broadband Array

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Broadband Array

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Broadband Array

200 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


Switched Antenna

  • Objective

    • Extend bandwidth of 5:1 antenna via switching

  • Strategy

    • Switch in various loaded wire segments

    • Optimize for lower frequency band

    • Open switch, examine effects on 5:1 band

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Loaded Segment

LoadedSegment

Switch

Switch

5:1 Antenna

5:1 Antenna

Switch Open for 5:1 Band

Switch Closed for New Band

Switching Antenna

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Switching Antenna

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Switching Antenna

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Conclusions

  • Broadband Array

    • Broadband performance can be maintained

  • Switching Antenna

    • Bandwidth can be increased

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


Further Research

  • Broadband Array

    • Feedline between matching network and array elements

    • Matching network

  • Switching Antenna

    • Switching mechanism

    • Software modifications

NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC


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