EFFECT OF SWITCH FAILURE ON THE PERFORMANCE OF A SELF- STRUCTURING - PDF document

EFFECT OF SWITCH FAILURE ON THE PERFORMANCE OF A SELF- STRUCTURING ANTENNA B. T. Perry*, C.M. Cole- J. E. Ross L.L. Nagy man E. J. Rothwell, and John Ross & Associates MC 483-478-105 L.C. Kempel 350 West 800 North Delphi Research Labs ECE Department Suite 317 51786 Shelby Pkway Michigan State University Salt Lake City, Utah 84103 Shelby Township, MI East Lansing, MI 48824 johnross@johnross.com 48316 rothwell@egr.msu.edu Antennas are often deployed in difficult environmental conditions, where their physical degradation, alteration, or misuse results in decreased electrical performance. In many consumer applications these antennas are difficult to replace or to repair. A Self-structuring antenna (SSA) is capable of responding to changes in its physical structure or to its environment by altering its electrical shape through the opening and closing of switches on an antenna template. The template consists of conducting wires or patches interconnected by N electronic or electro-mechanical switches that are controlled by a microprocessor. When the operating conditions change, the microprocessor searches through the 2 N possible electrical configurations to find a state with acceptable antenna performance. The successful operation of an SSA depends on the wide variation of its antenna properties, and this in turn depends on the number and position of its switches. It is anticipated that, over the lifetime of the antenna, one or more of the switches may fail or degrade in electrical performance. The template should be designed in such a way that no switch, or group of switches, is crucial to the effective operation of the SSA. That is, if certain switches fail, the performance of the SSA should degrade in a predictable way, such that it does not fall below some minimum acceptable level. This paper investigates the effect of switch failure for a standard SSA template (C. M. Coleman, E. J. Rothwell, and J. E. Ross, IEEE AP-S Int. Symp. , Salt Lake City, Utah, 2000). Performance criteria such as input impedance, standing wave ratio, and antenna pattern uniformity are examined using both experimental and numerical data. Because the number of template configurations is very large for reasonable values of N, the SSA performance is analyzed statistically, by taking a sample from the total population of template configurations.

EFFECT OF SWITCH FAILURE ON THE PERFORMANCE OF A SELF- STRUCTURING ANTENNA B. T. Perry*, C.M. Cole- J. E. Ross L.L. Nagy man E. J. Rothwell, and John Ross & Associates MC 483-478-105 L.C. Kempel 350 West 800 North Delphi Research Labs ECE Department Suite 317 51786 Shelby Pkway Michigan State University Salt Lake City, Utah 84103 Shelby Township, MI East Lansing, MI 48824 johnross@johnross.com 48316 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 4. New knowledge contributed by paper: This is the first study of the effect of switch failure on the performance of a self-structuring antenna. 5. Relationship to previous work: Self-structuring antennas were introduced by the authors at the 2000 and 2001 URSI National Radio Science Meetings. The basic operation of the antenna was described in these papers.

MSU Electromagnetics Lab EM LAB EM LAB Effect of Switch Failure on the Performance of a Self-Structuring Antenna B.T. Perry*, C.M. Coleman, E.J. Rothwell, L.C. Kempel Department of Electrical and Computer Engineering Michigan State University, East Lansing, MI J.E. Ross John Ross & Associates, Salt Lake City, UT L.L.Nagy Delphi Research Labs, Shelby Township, MI (URSI Session) (day), June (16-21), 2002 (time) ( location ) June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna 1

Overview EM LAB EM LAB � Self-Structuring Antenna (SSA) Overview � Goal � Test Setup and Procedure � Single Switch Failures and Consequences � Multiple Switch Failures and Consequences � Conclusions and Future Work June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna 2

SSA Related Publications EM LAB EM LAB C. M. Coleman, E. J. Rothwell, and J.E. Ross, “Self-structuring antennas,” IEEE AP-S International Symposium and URSI Radio Science Meeting, Salt Lake City, Utah, July 16-21, 2000. J. E. Ross, E. J. Rothwell, C. M. Coleman, and L. L. Nagy, “Numerical simulation of self- structuring antennas based on a genetic algorithm optimization scheme,” IEEE AP-S International Symposium and URSI Radio Science Meeting, Salt Lake City, Utah, July 16-21, 2000. C. M. Coleman, E.J. Rothwell, J.E. Ross, and L.L. Nagy, “Application of Two-Level Evolutionary Algorithms to Self-Structuring Antennas,” IEEE AP-S International Symposium and URSI Radio Science Meeting, Boston,Massachusetts, July 8-13, 2001. B. T. Perry, C. M. Coleman, B. F. Basch, E.J. Rothwell, J.E. Ross, and L.L. Nagy, “Self-Structuring Antenna for Television Reception,” IEEE AP-S International Symposium and URSI Radio Science Meeting, Boston, Massachusetts, July 8-13, 2001. C. M. Coleman, E. J. Rothwell, J. E. Ross, and L. L. Nagy, “Self-Structuring Antennas,” IEEE Antennas and Propagation Magazine, accepted for publication. June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna 3

SSA Overview EM LAB EM LAB � The SSA automatically configures itself to accommodate changes in signal strength, orientation, and atmospheric conditions through the control of simple on/off switches � Structuring of the SSA takes place through the use of a microcontroller, utilizing non-latching, single coil relays controlled through the output ports � Changes in switch states cause the electrical shape of the antenna to be altered, allowing it to adjust to changes in its electromagnetic environment � The effect of different antenna configurations is unknown to the designer, only a statistical approach is utilized in testing June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna 4

SSA Board Layout EM LAB EM LAB Antenna Elements Switches Relay Driver Hardware Microcontroller Interface Antenna Feed June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna 5

Goal EM LAB EM LAB � Determination of the impact of switch failures on the performance of self- structuring antennas � Investigation of consequences regarding single and multiple switch failures � Evaluation of predictability of degradation in performance due to switch failure June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna 6

Test Setup and Procedure EM LAB EM LAB • Testing was done using the HP-8720 network analyzer • 10,000 known 24 bit random numbers were used to set the states of the antenna for each frequency set tested (50-450 MHz) • From the experimental data, switch failure analysis was performed for each single switch failure, as well as failures of 2 switches simultaneously June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna 7

Single Switch Failures EM LAB EM LAB • In order to quantify the effect of switch failure, we define: GoodStates frac ( f ) = AvailableS tates • Good States are defined as those switch combinations with SWR ≤ ≤ 2.0 ≤ ≤ • Available States are combinations that the antenna is able to be placed into • The number of available states is roughly cut in half by each switch failure June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna 8

Single Switch Failures EM LAB EM LAB • If frac(f) functions remain constant, or change in a minimal way under switch failure, then the antenna is said to degrade only in algorithm efficiency, due to change in the number of available good states • If frac(f) functions change in an intermediate fashion, i.e., small changes at discrete frequencies, then the antenna degrades in an expected fashion, with minimal change in the fraction of good states and degradation in algorithm efficiency • If frac(f) functions experience large changes, the antenna degrades in an unacceptable fashion, both in the fraction of good states and efficiency of the algorithm June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna 9

Single Switch Failures EM LAB EM LAB Switch 1 Switch 2 June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna10

Single Switch Failures EM LAB EM LAB Switch 3 Switch 4 June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna11

Single Switch Failures EM LAB EM LAB Switch 5 Switch 6 June (16-20), 2002 2002 AP-S/URSI Symposium -- Effect of Switch Failure on the Performance of a Self-Structuring Antenna12