A COMPARISON OF SEVERAL SELF-STRUCTURING ANTENNA TEMPLATES B. T. Perry*, J.A. Nanzer J. E. Ross L.L. Nagy and E.J. Rothwell John Ross & Associates Delphi Research Labs ECE Department 422 N. Chicago Street 51786 Shelby Pkwy Michigan State University Salt Lake City, Utah Shelby Township, MI East Lansing, MI 48824 johnross@johnross.com rothwell@egr.msu.edu Successful operation of a self-structuring antenna (SSA) depends both on the large number of available antenna states, and the underlying characteristics of the antenna template. For example, if an antenna template is too small, an SSA likely won’t perform well for low frequency applications, regardless of the switch states. Another possibility is that an SSA template is of appropriate size; in this case, the performance of the antenna depends on both the switch states and the configuration of the antenna elements. Up to this point, the effect of the underlying characteristics of the antenna template, i.e., the configuration of the antenna elements, has not been thoroughly studied. This paper looks to characterize the effect of the SSA template layout, using measured data such as standing wave ratio (SWR), antenna patterns, and input impedance. By finding the effect of template layout on the performance of the SSA, guidelines can be created by which future layouts can be designed. Through this process, self- structuring antenna templates can be custom designed to better fit particular applications. This paper uses measured performance criteria to compare and contrast several SSA template designs. These designs include a “standard”, linearly spaced SSA template, as described in previous work, a variation based on a log-periodic design, and several templates that are fairly application specific. The application specific templates are configured such that all switches and control hardware are aligned along one edge of the template. This allows the SSA to be used in applications where the placement of both the feed network and the switches are desired to be hidden away.
A COMPARISON OF SEVERAL SELF-STRUCTURING ANTENNA TEMPLATES B. T. Perry*, J.A. Nanzer J. E. Ross L.L. Nagy and E.J. Rothwell John Ross & Associates Delphi Research Labs ECE Department 422 N. Chicago Street 51786 Shelby Pkwy Michigan State University Salt Lake City, Utah Shelby Township, MI East Lansing, MI 48824 johnross@johnross.com rothwell@egr.msu.edu 1. Commission and session topic: B1.1 Antenna Analysis and Design 2. Required presentation equipment: PowerPoint display 3. Corresponding author: Edward J. Rothwell Department of Electrical and Computer Engineering Michigan State University East Lansing, MI 48824 Phone: 517-355-5231 e-mail: rothwell@egr.msu.edu FAX: 517-353-1980 6. New knowledge contributed by paper: This is the first comprehensive comparison of differing self-structuring antenna template designs utilizing measured data. 7. Relationship to previous work: Self-structuring antennas were introduced by the authors at the 2000, 2001, and 2002 URSI National Radio Science Meetings. The basic operation and analysis of the antenna were described in these papers.
MSU EM Group A Comparison of Several Self-Structuring Antenna Templates B.T. Perry, J.A. Nanzer*, E.J. Rothwell, L.C. Kempel Michigan State University J.E. Ross, John Ross and Associates L.L. Nagy, Delphi Research Labs URSI B Session 56 Tuesday June 24, 8:20 am, Knox June 24, 2003 A Comparison of Several SSA Templates 1
Overview of Presentation • Introduction to Self-Structuring Antennas (SSAs) • Description of templates • Measured SWR results • Measured pattern results • Conclusions June 24, 2003 A Comparison of Several SSA Templates 2
Self-Structuring Antenna Concept • Self-Structuring Antenna system: o Re-optimizes itself when its electromagnetic environment changes o Arranges itself into a large number of possible antenna configurations o Uses information from a receiver or sensor to determine fitness of each configuration and determines future configurations o Searches through possible configurations using binary search routine such as; Genetic algorithms (GAs) Simulated annealing (SA) Ant colony optimization (ACO) June 24, 2003 A Comparison of Several SSA Templates 3
Self-Structuring Antenna (SSA) June 24, 2003 A Comparison of Several SSA Templates 4
Self-Structuring Antenna Template • A self-structuring antenna template is comprised of a large number of wire segments or patches interconnected by controllable switches • For each configuration, the states of the switches determine the electrical characteristics of the antenna • For a template with n switches, there are 2 n possible configurations • An asymmetric topology provides more diversity and less repeated states than a symmetric topology June 24, 2003 A Comparison of Several SSA Templates 5
Templates studied • Four different templates were studied o “Standard” template o Log-periodic design o Edge-switch template 1 o Edge-switch template 2 • Templates with switches located along the edge may prove more useful for automotive applications • Templates with switches concentrated near the feed may be less affected by switch failures June 24, 2003 A Comparison of Several SSA Templates 6
Templates studied • “Standard” template • 32 switches = 4.3 billion combinations • 16`` x 22`` June 24, 2003 A Comparison of Several SSA Templates 7
Templates studied • Log-periodic template • 32 switches • 16`` x 22`` June 24, 2003 A Comparison of Several SSA Templates 8
Templates studied • Edge- switched Type 1 • 32 switches • 16`` x 22`` June 24, 2003 A Comparison of Several SSA Templates 9
Templates studied • Edge- switched Type 2 • 32 switches • 16`` x 22`` June 24, 2003 A Comparison of Several SSA Templates 10
SWR measurements • Experimental setup • Measure 30,000 independent antenna states • Look at statistical distribution of SWR values • SWR calculated relative to 200 Ω Ω Ω Ω June 24, 2003 A Comparison of Several SSA Templates 11
SWR measurements 100 70 50 40 30 20 % of states at or below SWR 10 7 5 E1 4 3 Standard 2 E2 S 1 L 0.7 0.5 0.4 0.3 0.2 0.1 0.07 error bars show 95% confidence interval 0.05 0.04 0.03 50 MHz 0.02 Log-periodic 0.01 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 SWR June 24, 2003 A Comparison of Several SSA Templates 12
SWR measurements 100 70 50 40 30 20 % of states at or below SWR 10 7 5 4 S 3 Edge 1 E2 E1 2 L 1 0.7 0.5 0.4 0.3 0.2 0.1 0.07 error bars show 95% confidence interval 0.05 0.04 0.03 100 MHz 0.02 Edge 2 0.01 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 SWR June 24, 2003 A Comparison of Several SSA Templates 13
SWR measurements 100 70 50 40 30 20 % of states at or below SWR E2 10 S 7 E1 5 4 L 3 2 1 0.7 0.5 0.4 0.3 0.2 0.1 0.07 error bars show 95% confidence interval 0.05 0.04 0.03 150 MHz 0.02 0.01 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 SWR June 24, 2003 A Comparison of Several SSA Templates 14
SWR measurements 100 70 50 E1 40 30 S 20 % of states at or below SWR 10 7 5 L 4 3 2 E2 1 0.7 0.5 0.4 0.3 0.2 0.1 0.07 error bars show 95% confidence interval 0.05 0.04 0.03 300 MHz 0.02 0.01 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 SWR June 24, 2003 A Comparison of Several SSA Templates 15
SWR measurements 100 70 50 E2 40 30 20 E1 L % of states at or below SWR 10 S 7 5 4 3 2 1 0.7 0.5 0.4 0.3 0.2 0.1 0.07 error bars show 95% confidence interval 0.05 0.04 0.03 400 MHz 0.02 0.01 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 SWR June 24, 2003 A Comparison of Several SSA Templates 16
SWR measurements 100 70 50 E2 40 30 20 S % of states at or below SWR L 10 E1 7 5 4 3 2 1 0.7 0.5 0.4 0.3 0.2 0.1 0.07 error bars show 95% confidence interval 0.05 0.04 0.03 500 MHz 0.02 0.01 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 SWR June 24, 2003 A Comparison of Several SSA Templates 17
SWR measurements 100 70 50 40 30 20 L % of states at or below SWR 10 7 5 E1 4 S 3 Standard E2 2 1 0.7 0.5 0.4 0.3 0.2 0.1 0.07 error bars show 95% confidence interval 0.05 0.04 0.03 600 MHz 0.02 Log-periodic 0.01 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 SWR June 24, 2003 A Comparison of Several SSA Templates 18
SWR measurements 100 70 50 40 30 L 20 % of states at or below SWR 10 7 E1 5 4 3 Edge 1 2 1 E2 0.7 0.5 0.4 0.3 0.2 0.1 0.07 error bars show 95% confidence interval 0.05 0.04 0.03 700 MHz 0.02 Edge 2 0.01 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 SWR June 24, 2003 A Comparison of Several SSA Templates 19
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