1. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 1 Broadband Arrays and Switching Antennas Dan Palecek, SD School of Mines and Technology, Rapid City, SD Dr. Anthony Martin, Clemson University, Clemson, SC

2. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 2 Overview Background  Simulation Software  Genetic Algorithms  5:1 Antenna System Objectives and Strategies / Results  Broadband Array  Switching Antenna Conclusions and Further Research

3. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 3 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

4. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 4 How Do GAs Work? Encode Parameters Generate Initial Population Evaluate and Assign Fitness Values Select Parents Based on Fitness Reproduce Through Recombination Mutation Chromosome p1p1 {{{ p2p2 p3p3 p4p4 [ 0101 0011 1101 0101 ] {

5. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 5 5:1 Antenna System L = 0.22  H R = 470  a = 0.4 mm 2a LR h L = 11.6 cm h = 21.25 cm

6. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 6 5:1 Antenna System  Matching Network LmLm ZAZA Transmission Line Z 0 = 50  1 : 4

7. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 7 5:1 Antenna System Bandwidth criteria  VSWR < 3.5  System gain > -4.0 dBi Cost Function - VSWR and Gain Penalty

8. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 8 5:1 Antenna System

9. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 9 5:1 Antenna System

10. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 10 Broadband Array Objective  Determine if array retains broadband characteristics Strategy  Place 5:1 elements in array configuration  Vary spacing between elements and observe effects

11. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 11 Broadband Array h = 21.25 cm h L = 11.6 cm d

12. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 12 Broadband Array Matching Network Transmission Line Z 0 = 50  1 : 2 LmLm ZAZA ZAZA 

13. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 13 Broadband Array

14. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 14 Broadband Array

15. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 15 Broadband Array 200 MHz300 MHz400 MHz 500 MHz600 MHz700 MHz 800 MHz900 MHz1000 MHz

16. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 16 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

17. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 17 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

18. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 18 Switching Antenna

19. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 19 Switching Antenna

20. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 20 Conclusions Broadband Array  Broadband performance can be maintained Switching Antenna  Bandwidth can be increased

21. NSF SURE Program, Summer 2002 / Clemson University, Clemson, SC 21 Further Research Broadband Array  Feedline between matching network and array elements  Matching network Switching Antenna  Switching mechanism  Software modifications