Date post: | 31-Dec-2015 |
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Predicting Electromagnetic Fields with GEMACS and the
CEM Framework
Edgar L. CoffeyApplied Research Associates, Inc.
Ground Vehicle Antenna Radiation
Center-fed at 50 Watts
Ground Vehicle Radiation Problem
• Modeling Scenario– Antenna on vehicle over ground plane– Radiates in all directions
• Observables– Find where radiation levels are “excessive”
• Steps– Build an EM model of the scene– Execute GEMACS to find fields– Extract desired observables from raw data– Use SmartView to render the results
Start with the Vehicle
Main Menu• Edit• Add Element to Scene• Geometry
Select geometry file
Set rendering features
Set position at origin
Add the Ground Plane
Main Menu• Edit• Add Element to Scene• Ground plane
Select geometry fileSet conductivity = 0.005Set rendering size = 100 m
Excite the Antenna with 50 Watts
Main Menu• Edit• Add Element to Scene• Impressed Source
Value = 73.38 + j0 voltsSegment No. 16Frequency = 50 MHz(No load)
Request Surface Currents
Main Menu• Edit• Add Element to Scene• Surface/Wire Currents
Value = 73.38 + j0 voltsSelect Results File
Request Near-Zone Electric Fields
-40 m < X < 40 m-40 m < Y < 40 m 0 m < Z < 26 mdx = dy = dz = 2 m
(Only a small part of the lattice is shown.)
Export to GEMACS and Run
(Hand-generated GEMACS input shown for clarity.)
Main Menu• File• Export• GEMACS
Enter file name
Main Menu•Execute•Launch GEMACS 6.11
Field Output Request
Frequency and Excitation
Segment and Conductivity
Results XML File
Post-Process GEMACS’ Data
The Framework’s Component View tool easily generates requested observables
Generating Surface Currents
Use Component View to post-process data, then view with SmartView
Visualizing Surface Currents
(Currents are color-coded according to their intensity.)
Generating Contour Maps
The full 3D field data set is read into Component View via XMLReader, then the user selects a “cut plane” on which to generate contours. The data are written to a SmartView-compatible file.
Visualizing Contours of Fields
• Rendered with AE’s SmartView.
• Viewing contours from above.
• Vehicle forward direction is +x axis.
• YZ-plane is vehicle’s front face
• Contour is taken at z = 2 m
• Color scale units are in Volts/meter
Generating IsoSurface ContoursThis map generates two surface and combines them with the vehicle
Visualizing IsoContour Surfaces
5 V/m surface
2 V/m surface
(Front of contours removed for clarity)
Using Light to Enhance the View
(Previous figure viewed from below)
Combining Contours with IsoSurfaces (color mapped)
Summary of Ground Vehicle Simulation and Visualization
• Building the scene (15 minutes)
• Predicting fields (25 minutes)
• Post-processing the data (15 minutes)
• Visualization and Screenshots (20 minutes)
• All was done on a laptop PC with GEMACS and the CEM Framework