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

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

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

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 [ ] {

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 = cm

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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