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Slide 1
Dr. Er ic K . Wal tonThe Ohio State Univers i ty ; E lectroSc ience
LaboratoryColumbus , Ohio 43212
Wal ton [email protected]
Dr. Wladimiro Vi l l arroe lAGC Automot ive Amer icas R&D
Yps i lant i , MI 48197WVi l larroe l@us .agc-automot ive .com
Multi-Parametric Antenna Test Visualization for Optimization
Session Information Here
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INTRODUCTIONThere are a large number of antennas needed for
modern automotive communications systems AM, FM, FM diversity TV & TV diversity Remote keyless entry/start Cellular; Bluetooth Automatic toll systems Smart highway information systems GPS and GPS information systems (traffic information) Radar systems (backup, side impact, lane departure, intelligent
cruise control)). Manufacturers are looking for ways to reduce the total number of
such antennas by using combinations of a smaller number of antennas.
This paper will discuss a software approach that permits the engineer to visualize the antenna performance effects of variations in geometry for a group of antennas based on either test data or simulation.
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ACKNOWLEDGEMENT
MUCH OF THIS WORK IS TAKEN FROM AN UNDERGRADUATE INTERN PROJECT BY
MR. RYAN TOKOLAA 2009 UNDERGRADUATE INTERNAT THE OHIO ST. UNIV. ELECTROSCIENCE
LAB.
THE PROJECT WAS SUPPORTED BY AGC AMERICA INC., YPSILANTI, MI.
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AGC AMERICA
Asahi Glass Company (AGC) A core Mitsubishi company World-class manufacturer and innovator in the
fields of glass and fluorine chemistry AGC Automotive Americas R&D, Inc.
AGC subsidiary in Ypsilanti, Michigan Dedicated to the development of new
technologies and new products for processed automotive glass
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Why Designing Car Antennas is Difficult
On-glass (conformal) antennas are becoming more popular Low-cost Easy to manufacture Unobtrusive
Limited available set of possible locations Must have minimal visual obstruction on side and rear
windows Limited to fade band of windshield
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Why Designing Car Antennas Is Difficult
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Even a simple antenna has a very large number of possible geometric distributions
Today's codes can predict the performance of an antenna, but not “design” an antenna
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EXAMPLE PARAMETRIC VARIABLES
FEED POINT LOCATION
INTERCONNECTION
LOCATION
ELEMENTLENGTHS
FOR EACH PARAMETER, THERE ARE DIFFERENCES IN THE GAIN PATTERN AND IMPEDANCES
THUS THERE ARE A VERY LARGE NUMBER OF POSSIBLE COMBINATIONS AND PERMUTATIONS
WE NEED A WAY TO CHOOSE THE BEST.
THERE IS ALSO AN ANTENNA IN THE FRONT OR SIDE
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VISUALIZATION MOTIVATION
Simply plugging a cost function into an optimization algorithm is insufficient. Human interaction (judgment) is required to: Refine the cost function Analyze the solution space and determine which
optimization algorithms are appropriate Identify regions of interest for optimization
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Software Outline
The software has the following sequence:1. Using
a. Theoretical modeling data setsb. Experimental measurement data sets.
2. Create a data set of antenna gain performance as a function ofa. Polarizationb. Frequencyc. Increments in antenna geometry
3. Graphically Display the Consequencesa. Gain vs. Azimuth vs. Antenna wire locationsb. Polarization vs. Azimuth vs. Antenna wire locationsc. Overall dual antenna gain vs. Azimuth
i. As diversityii. As phase combined
d. Cost function behaviori. Vs. wire and interconnect locationsii. Vs. antenna 1 and antenna 2
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GUI TO DEFINE PARAMETERSFOR A THEORETICAL MODEL (ESP5)
WE DEFINE ANTENNA WIRES WITH PARAMETRIC GEOMETRICAL INCREMENTS
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Setup and Simulation
Each endpoint may be swept in one or two directions
Example: [min = -4, step = 2, max = 4] results in five simulations with the wire endpoint at {-4, -2, 0, 2, 4}
step = 0 if not swept“xxxx” indicates unnecessary info (vert. wires have only one x-coordinate, horiz. wires have only one y-coordinate)
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DISPLAY THE WIRE LAYOUTFOR EACH ANTENNA
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DEFINE THE VEHICLEAND INSERT THE ANTENNA
USER CAN DOUBLE CHECK THE LAYOUTPRIOR TO THE (OVERNIGHT) CALCULATION
INSERTEDANTENNAS
VEHICLE WIRE GRID MODEL WITH INITIAL ANTENNA
GEOMETRY
E X A MP L E F
OR
S E DA N
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SUB-SCALE MEASUREMENTS
SUB-SCALE MEASUREMENTSFOR COMPARISON
GROUNDPLANE
NOTSHOWN
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Example Simulation for a Van:
GMC Van Mesh Wireframe with Front & Rear Antenna Apertures
Y
X
Z
Y
X
ZCreated using make car mesh of VAAR
EXAMPLE FOR VAN
Slide 16
Measurement of a full scale van
WE CAN COMPARE MEASUREMENT AND SIMULATION
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Data Visualization
User-defined functions have access to four arrays of data for each specific parameter combinations: FGth (Vertically polarized gain of front antenna) FGph (Horizontally polarized gain of front antenna) RGth (Vertically polarized gain of rear antenna) RGph (Horizontally polarized gain of rear antenna)
Each of these is a 1x360 array giving the 360° azimuthal antenna radiation pattern in dBi
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GUI FOR SETTING UPPARTICULAR VISUALIZATION
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Data Visualization
User-defined variables (a-f) can contain FGth, FGph, RGth, RGph, or any previous variable (b can contain a as an argument)
Any MATLAB functions (max, mean, etc.) can be used
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Comparing Data Visualizations
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EXAMPLE VISUALIZATION( AZIMUTH PLOTS)
FGph
a=FGphb=RGphc=max(a,b)d=FGthe=RGthf=max(d,e)Plot:Max(c,f)
a=FGthPlot(a)
a=RGphPlot(a)
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EXAMPLE: GAIN VS. FREQ. & AZIMUTH
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VISUALIZATIONS FORMEAN REAR GAIN (φ POL) AND MIN OF MAX
FREQ
WIRE LOCATION
a=RGphPlot(mean(a))
a=FGph; b=RGph; c=max(a,b)d=FGth; e=RGth; f=max(d,e)Plot(min(max(c,f))
Slide 24
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Optimum Antenna Configuration
Mean front antenna gain phi & theta of wire location vs.
frequency
Minimum front antenna gain phi & theta of wire location
vs. frequency
Maximum front antenna gain phi & theta of wire location
vs. frequency
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Conclusion (What I’ve Learned & Where I’m Going) Ryan’s code has shown a considerable amount of thought
and effort using programming and antenna theory to visualize & then optimize an antenna configuration on a vehicle.
Future studies Study various types of cost functions and there impact on
antenna configuration. Modify the code to allow the user to create only one antenna. Modify the code to allow the user to have an antenna with static
geometry. Finally we plan to discuss future project options with AGC
personnel.
Comments & Questions
Slide 26
References
[1] Kraus J. D. and R. J. Marhefka, Antennas for All Applications, 3rd Ed., McGraw-Hill, N.Y., N. Y., 2002.
[2] Abou-Jaoude, R., and Walton, E. K., “Numerical Modeling of On-Glass Conformal Automobile Antennas”, IEEE Trans. Antennas Prop., vol. 46, pp 845-852, June 1998
[3] Tokola, Ryan and Walton E. K., “Visualization Software for Vehicle Antenna Design,” OSU ElectroScience Laboratory Department of Electrical and Computer Engineering, Columbus, Ohio, Technical Report 60003388-1 and 60024198-1, January 29, 2010
[4] Newman, E.H., “A User’s Manual for The Electromagnetic Surface Patch Code ESP Version 5”, Technical Report 716199-1 1, The Ohio State University ElectroScience Laboratory, Department of Electrical Engineering, 1995
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