SIMULATION OF A FM BAND SELF-STRUCTURING … · simulation of a fm band self-structuring antenna in...
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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 [email protected] [email protected] 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.
Transcript of SIMULATION OF A FM BAND SELF-STRUCTURING … · simulation of a fm band self-structuring antenna in...
SIMULATION OF A FM BAND SELF-STRUCTURING ANTENNA IN ANAUTOMOBILE ENVIRONENT
B. T. Perry*, E.J. Rothwell J. E. Ross L.L. NagyECE Department John Ross & Associates Delphi Research LabsMichigan State University 422 N. Chicago Street 51786 Shelby PkwyEast Lansing, MI 48824 Salt Lake City, Utah Shelby Township, [email protected] [email protected]
Antennas are often placed in environments where their interaction withsurrounding objects effects their overall performance. Some are deployed inenvironments where the designer is unsure of the effect on the performance of theantenna. This is especially true in automotive applications where the car body, aswell as other components of the vehicle, play a role in the functionality of theantennas. Self-structuring antennas (SSAs) are subject to this uncertainty duringtheir design and analysis. For this reason, a simulation-based assessment of aself-structuring antenna placed in the rear window of an automobile wasundertaken.
Using GA-NEC, a software package developed by John Ross & Associates, thestates 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 theself-structuring antenna template. Variations in the switch states give rise tochanges in the electrical shape of the antenna, as described in previous work onthe 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 thedetermination of the fitness of a certain SSA state.
The simulation of SSAs presented here is meant to provide a cost effectiveapproach to the design of self-structuring antennas in environments that are notoptimal for performance of an antenna. This study helps to provide a frameworkfor a simulation-based approach to the study of self-structuring antennas invarious environments, including automotive applications. As a specific example,an SSA placed in the upper rear window of a vehicle is considered. The resultsare compared to the simulation of a passive backlight antenna placed in the sameenvironment.
SIMULATION OF A FM BAND SELF-STRUCTURING ANTENNA IN ANAUTOMOBILE ENVIRONENT
B. T. Perry*, E.J. Rothwell J. E. Ross L.L. NagyECE Department John Ross & Associates Delphi Research LabsMichigan State University 422 N. Chicago Street 51786 Shelby PkwyEast Lansing, MI 48824 Salt Lake City, Utah Shelby Township, [email protected] [email protected]
1. Commission and session topic: B1.1 Antenna Analysis and Design
2. Required presentation equipment: PowerPoint display
3. Corresponding author:Edward J. RothwellDepartment of Electrical and Computer EngineeringMichigan State UniversityEast Lansing, MI 48824Phone: 517-355-5231e-mail: [email protected]: 517-353-1980
6. New knowledge contributed by paper: This is the first comprehensiveexamination of the effect of an automobile on the performance of a self-structuringantenna.
7. Relationship to previous work: Self-structuring antennas were introduced bythe 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.
1June 24, 2003
Simulation of a FM Band Self-StructuringAntenna in an Automobile Environment
B.T. Perry*, E.J. Rothwell, L.C. KempelDepartment of Electrical and Computer Engineering
Michigan State University, East Lansing, MI
J.E. Ross John Ross & Associates, Salt Lake City, UTL.L.Nagy Delphi Research Labs, Shelby Township, MI
URSI B Session 56: Vehicle Electromagnetics and Inverse ScatteringTuesday, June 24, 2003 8:00 a.m. Knox
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 2
Overview
Self-Structuring Antenna (SSA) Overview
Goals
Motivation
Automobile Environment
Simulation Results
Conclusions
Future Work
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 3
SSA Overview
The SSA automatically configures itself to accommodate changes insignal strength, orientation, and atmospheric conditions through thecontrol of simple on/off switches
Changes in switch states cause the electrical shape of the antenna to bealtered, allowing it to adjust to changes in its electromagneticenvironment
The effect of different antenna configurations is unknown to thedesigner, only a statistical approach is utilized in testing
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 4
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, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 5
Motivation
High end automobiles built today can have 11 or more antennasFM Radio (multiple)
AM Radio (multiple)
GPS
Satellite Radio
Cellular Telephone
Keyless Entry
Television
Self-structuring antennas could be used to replace multiple antennasSavings in both money and space
Multitasking-broadband antennas
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 6
Automobile Environment
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 7
Automobile Environment
Heater Grid
Self-Structuring Antenna
Rear Window Frame
Antenna Feed
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 8
Simulation Results
Self-Structuring Antenna over
a ground plane
VSWR vs. Frequency
Optimized for constrained
VSWR between 1 and 3 across
the FM Band simultaneously
Approximate Antenna Size
0.33? by 0.05? at 100 MHz88 90 92 94 96 98 100 102 104 106 108
Frequency (MHz)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17VSWR
First ConfigurationSecond Configuration
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment 9
Simulation Results
Current Distribution for Self Structuring Antennaover a ground plane
92 MHz
VSWR of 1.56
VSWR of 15.8
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment10
Simulation Results
Self-Structuring Antenna on
Car without Heater Grid
VSWR vs. Frequency
88 90 92 94 96 98 100 102 104 106 108
Frequency (MHz)
1
2
3
4
5
6
7VSWR
First ConfigurationSecond Configuration
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment11
Simulation ResultsSSA on Car – 88 MHz
VSWR of 4.03 VSWR of 6.67
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment12
Simulation ResultsSSA on Car – 88 MHz
VSWR of 4.03 VSWR of 6.67
Elevation
E - ThetaE - Phi
Elevation
E - ThetaE - Phi
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment13
Simulation ResultsSSA on Car – 88 MHz
VSWR of 4.03 VSWR of 6.67
Azimuthal
E - Theta
Azimuthal
E - Theta
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment14
Simulation ResultsSSA on Car – 108 MHz
VSWR of 3.33 VSWR of 1.47
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment15
Simulation ResultsSSA on Car – 108 MHz
VSWR of 3.33 VSWR of 1.47
Azimuthal
E - Theta
Azimuthal
E - Theta
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment16
Simulation Results
SSA on Car with Heater Grid
VSWR vs. Frequency
88 90 92 94 96 98 100 102 104 106 108
Frequency (MHz)
1
2
3
4VSWR
First ConfigurationSecond Configuration
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment17
Simulation ResultsSSA and Heater on Car – 88 MHz
VSWR of 3.19 VSWR of 2.71
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment18
Simulation ResultsSSA and Heater on Car – 88 MHz
VSWR of 3.19 VSWR of 2.71
Azimuthal
E - Theta
Azimuthal
E - Theta
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment19
Simulation ResultsSSA and Heater on Car - 108 MHz
VSWR of 1.50 VSWR of 3.99
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment20
Simulation ResultsSSA and Heater on Car - 108 MHz
VSWR of 1.50 VSWR of 3.99
Azimuthal
E - Theta
Azimuthal
E - Theta
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment21
Simulation Results
Self Structuring Antenna on Car without Heater GridOptimized for VSWR less than 1.1 at individual frequencies
11.11.21.31.41.51.61.71.81.9
2
88 92 96 100 104 108
Frequency (MHz)
VSW
R
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment22
Simulation Results
Self Structuring Antenna on Car without Heater Grid – 88 MHzOptimized for VSWR less than 1.1 at individual frequencies
Elevation - 88 MHz
E - ThetaE - Phi
Azimuthal - 88 MHz
E - Theta
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment23
Simulation Results
Self Structuring Antenna on Car without Heater Grid – 108 MHzOptimized for VSWR less than 1.1 at individual frequencies
Elevation - 108 MHz
E - ThetaE - Phi
Azimuthal - 108 MHz
E - Theta
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment24
Simulation Results
Self Structuring Antenna on Car with Heater GridOptimized for VSWR less than 1.1 at individual frequencies
11.11.21.31.41.51.61.71.81.9
2
88 92 96 100 104 108
Frequency (MHz)
VSW
R
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment25
Simulation Results
Self Structuring Antenna on Car with Heater Grid – 88 MHzOptimized for VSWR less than 1.1 at individual frequencies
Elevation - 88 MHz
E - ThetaE - Phi
E - Theta
Azimuthal - 88 MHz
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment26
Simulation Results
Self Structuring Antenna on Car with Heater Grid – 108 MHzOptimized for VSWR less than 1.1 at individual frequencies
Elevation - 108 MHz
E - ThetaE - Phi
Azimuthal - 108 MHz
E - Theta
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment27
Conclusions
Algorithm converged faster and to a lower VSWR for increasinglycomplex environments when optimized for the entire FM Band
VSWR decreased when the SSA interacted strongly with the Car andHeater Grid
Optimization at individual frequencies yielded better results, i.e. lowerVSWR and better convergence, than optimizing for the entire FM Band
June 24, 20032003 AP-S/URSI Symposium -- Simulation of a FM Band Self-Structuring Antenna in an Automobile Environment28
Future Work
Optimization based on pattern measurements and VSWR simultaneously
Study of various switch models
Alternative placement of the SSA
