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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

Broadband Arrays and Switching Antennas

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

Dr. Anthony Martin, Clemson University, Clemson, SC


Overview
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
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
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
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 system1
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 system2
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 system3
5:1 Antenna System

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


5 1 antenna system4
5:1 Antenna System

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


Broadband array
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 array1
Broadband Array

h = 21.25 cm

hL = 11.6 cm

d

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


Broadband array2
Broadband Array

Matching Network

TransmissionLine

ZA

1 : 2

Z0 = 50 W

Lm

ZA

G

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


Broadband array3
Broadband Array

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


Broadband array4
Broadband Array

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


Broadband array5
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
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


Switching antenna

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 antenna1
Switching Antenna

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


Switching antenna2
Switching Antenna

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


Conclusions
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
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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