SIMULATION OF A FM BAND SELF-STRUCTURING ANTENNA IN AN AUTOMOBILE ENVIRONENT B. T. Perry*, E.J. Rothwell J. E. Ross L.L. Nagy ECE Department John Ross & Associates Delphi Research Labs Michigan State University 422 N. Chicago Street 51786 Shelby Pkwy East Lansing, MI 48824 Salt Lake City, Utah Shelby Township, MI rothwell@egr.msu.edu johnross@johnross.com Antennas are often placed in environments where their interaction with surrounding objects effects their overall performance. Some are deployed in environments where the designer is unsure of the effect on the performance of the antenna. This is especially true in automotive applications where the car body, as well as other components of the vehicle, play a role in the functionality of the antennas. Self-structuring antennas (SSAs) are subject to this uncertainty during their design and analysis. For this reason, a simulation-based assessment of a self-structuring antenna placed in the rear window of an automobile was undertaken. Using GA-NEC, a software package developed by John Ross & Associates, the states of the self-structuring antenna are chosen by way of a genetic algorithm. Chromosomes used in the GA consist of the states of switches residing on the self-structuring antenna template. Variations in the switch states give rise to changes in the electrical shape of the antenna, as described in previous work on the subject of SSAs. Analysis is done using NEC in the FM band (88-108MHz). Performance criteria such as input impedance, VSWR, and gain are used in the determination of the fitness of a certain SSA state. The simulation of SSAs presented here is meant to provide a cost effective approach to the design of self-structuring antennas in environments that are not optimal for performance of an antenna. This study helps to provide a framework for a simulation-based approach to the study of self-structuring antennas in various environments, including automotive applications. As a specific example, an SSA placed in the upper rear window of a vehicle is considered. The results are compared to the simulation of a passive backlight antenna placed in the same environment.
SIMULATION OF A FM BAND SELF-STRUCTURING ANTENNA IN AN AUTOMOBILE ENVIRONENT B. T. Perry*, E.J. Rothwell J. E. Ross L.L. Nagy ECE Department John Ross & Associates Delphi Research Labs Michigan State University 422 N. Chicago Street 51786 Shelby Pkwy East Lansing, MI 48824 Salt Lake City, Utah Shelby Township, MI rothwell@egr.msu.edu johnross@johnross.com 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 examination of the effect of an automobile on the performance of a self-structuring antenna. 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.
Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment B.T. Perry*, 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 B Session 56: Vehicle Electromagnetics and Inverse Scattering Tuesday, June 24, 2003 8:00 a.m. Knox June 24, 2003 1
Overview � Self-Structuring Antenna (SSA) Overview � Goals � Motivation � Automobile Environment � Simulation Results � Conclusions � Future Work June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 2
SSA Overview � The SSA automatically configures itself to accommodate changes in signal strength, orientation, and atmospheric conditions through the control of simple on/off switches � 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 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 3
Goals of Research � Application of self-structuring antennas in automobile environments � Gauge the interaction of the self-structuring antenna with components of the automobile, such as the heater grid and the car body June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 4
Motivation � High end automobiles built today can have 11 or more antennas � FM Radio (multiple) � AM Radio (multiple) � GPS � Satellite Radio � Cellular Telephone � Keyless Entry � Television � Self-structuring antennas could be used to replace multiple antennas � Savings in both money and space � Multitasking-broadband antennas June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 5
Automobile Environment June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 6
Automobile Environment Self-Structuring Antenna Antenna Feed Heater Grid Rear Window Frame June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 7
Simulation Results � Self-Structuring Antenna over VSWR 17 a ground plane 16 15 14 First Configuration � VSWR vs. Frequency Second Configuration 13 12 11 � Optimized for constrained 10 9 8 VSWR between 1 and 3 across 7 6 the FM Band simultaneously 5 4 3 � Approximate Antenna Size 2 1 88 90 92 94 96 98 100 102 104 106 108 � 0.33? by 0.05? at 100 MHz Frequency (MHz) June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 8
Simulation Results � Current Distribution for Self Structuring Antenna over a ground plane � 92 MHz � VSWR of 1.56 � VSWR of 15.8 June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 9
Simulation Results � Self-Structuring Antenna on VSWR 7 Car without Heater Grid 6 First Configuration Second Configuration 5 � VSWR vs. Frequency 4 3 2 1 88 90 92 94 96 98 100 102 104 106 108 Frequency (MHz) June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 10
Simulation Results SSA on Car – 88 MHz � VSWR of 4.03 � VSWR of 6.67 June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 11
Simulation Results SSA on Car – 88 MHz � VSWR of 4.03 � VSWR of 6.67 Elevation Elevation E - Theta E - Theta E - Phi E - Phi June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 12
Simulation Results SSA on Car – 88 MHz � VSWR of 4.03 � VSWR of 6.67 Azimuthal Azimuthal E - Theta E - Theta June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 13
Simulation Results SSA on Car – 108 MHz � VSWR of 3.33 � VSWR of 1.47 June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 14
Simulation Results SSA on Car – 108 MHz � VSWR of 3.33 � VSWR of 1.47 Azimuthal Azimuthal E - Theta E - Theta June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 15
Simulation Results � SSA on Car with Heater Grid VSWR 4 First Configuration Second Configuration � VSWR vs. Frequency 3 2 1 88 90 92 94 96 98 100 102 104 106 108 Frequency (MHz) June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 16
Simulation Results SSA and Heater on Car – 88 MHz � VSWR of 3.19 � VSWR of 2.71 June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 17
Simulation Results SSA and Heater on Car – 88 MHz � VSWR of 3.19 � VSWR of 2.71 Azimuthal Azimuthal E - Theta E - Theta June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 18
Simulation Results SSA and Heater on Car - 108 MHz � VSWR of 1.50 � VSWR of 3.99 June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 19
Simulation Results SSA and Heater on Car - 108 MHz � VSWR of 1.50 � VSWR of 3.99 Azimuthal Azimuthal E - Theta E - Theta June 24, 2003 2003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 20
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