Multi-Parametric Antenna Test Visualization for Optimization Session Information Here Dr. Eric K. Walton The Ohio State University; ElectroScience Laboratory Columbus, Ohio 43212 Walton.1@osu.edu Dr. Wladimiro Villarroel AGC Automotive Americas R&D Ypsilanti, MI 48197 WVillarroel@us.agc-automotive.com

INTRODUCTION There 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.

ACKNOWLEDGEMENT MUCH OF THIS WORK IS TAKEN FROM AN UNDERGRADUATE INTERN PROJECT BY MR. RYAN TOKOLA A 2009 UNDERGRADUATE INTERN AT THE OHIO ST. UNIV. ELECTROSCIENCE LAB. THE PROJECT WAS SUPPORTED BY AGC AMERICA INC., YPSILANTI, MI.

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 4

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 5

Why Designing Car Antennas Is Difficult 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 6

EXAMPLE PARAMETRIC VARIABLES INTERCONNECTION LOCATION FEED POINT LOCATION THERE IS ALSO AN ANTENNA IN THE FRONT OR SIDE ELEMENT LENGTHS 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.

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 8

Software Outline The software has the following sequence: Using Theoretical modeling data sets Experimental measurement data sets. Create a data set of antenna gain performance as a function of Polarization Frequency Increments in antenna geometry Graphically Display the Consequences Gain vs. Azimuth vs. Antenna wire locations Polarization vs. Azimuth vs. Antenna wire locations Overall dual antenna gain vs. Azimuth As diversity As phase combined Cost function behavior Vs. wire and interconnect locations Vs. antenna 1 and antenna 2

GUI TO DEFINE PARAMETERS FOR A THEORETICAL MODEL (ESP5) WE DEFINE ANTENNA WIRES WITH PARAMETRIC GEOMETRICAL INCREMENTS

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)

DISPLAY THE WIRE LAYOUT FOR EACH ANTENNA

DEFINE THE VEHICLE AND INSERT THE ANTENNA VEHICLE WIRE GRID MODEL WITH INITIAL ANTENNA GEOMETRY INSERTED ANTENNAS EXAMPLE FOR SEDAN USER CAN DOUBLE CHECK THE LAYOUT PRIOR TO THE (OVERNIGHT) CALCULATION

SUB-SCALE MEASUREMENTS FOR COMPARISON GROUND PLANE NOT SHOWN

Example Simulation for a Van: 15 Example Simulation for a Van: Created using make car mesh of VAAR Z Z Y X X Y EXAMPLE FOR VAN GMC Van Mesh Wireframe with Front & Rear Antenna Apertures

Measurement of a full scale van WE CAN COMPARE MEASUREMENT AND SIMULATION

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 17

GUI FOR SETTING UP PARTICULAR VISUALIZATION

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 19

Comparing Data Visualizations

EXAMPLE VISUALIZATION ( AZIMUTH PLOTS) FGph a=FGth Plot(a) a=FGph b=RGph c=max(a,b) d=FGth e=RGth f=max(d,e) Plot:Max(c,f) a=RGph Plot(a)

EXAMPLE: GAIN VS. FREQ. & AZIMUTH

VISUALIZATIONS FOR MEAN REAR GAIN (φ POL) AND MIN OF MAX a=RGph Plot(mean(a)) WIRE LOCATION a=FGph; b=RGph; c=max(a,b) d=FGth; e=RGth; f=max(d,e) Plot(min(max(c,f)) FREQ

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

Conclusion (What I’ve Learned & Where I’m Going) 25 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

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