Predicting Electromagnetic Fields with GEMACS and the CEM Framework

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Predicting Electromagnetic Fields with GEMACS and
the CEM Framework

• Edgar L. Coffey
• Applied Research Associates, Inc.
• bcoffey_at_ara.com

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Ground Vehicle Antenna Radiation
Center-fed at 50 Watts
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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

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Start with the Vehicle

• Main Menu
• Edit
• Add Element to Scene
• Geometry
• Select geometry file
• Set rendering features
• Set position at origin

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Add the Ground Plane

• Main Menu
• Edit
• Add Element to Scene
• Ground plane
• Select geometry file
• Set conductivity 0.005
• Set rendering size 100 m

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Excite the Antenna with 50 Watts

• Main Menu
• Edit
• Add Element to Scene
• Impressed Source
• Value 73.38 j0 volts
• Segment No. 16
• Frequency 50 MHz
• (No load)

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Request Surface Currents

• Main Menu
• Edit
• Add Element to Scene
• Surface/Wire Currents
• Value 73.38 j0 volts
• Select Results File

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Request Near-Zone Electric Fields
-40 m lt X lt 40 m -40 m lt Y lt 40 m 0 m lt Z lt 26
m dx dy dz 2 m
(Only a small part of the lattice is shown.)
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Export to GEMACS and Run

• Main Menu
• File
• Export
• GEMACS
• Enter file name
• Main Menu
• Execute
• Launch GEMACS 6.11

Frequency and Excitation
Segment and Conductivity
Field Output Request
Results XML File
(Hand-generated GEMACS input shown for clarity.)
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Post-Process GEMACS Data
The Frameworks Component View tool easily
generates requested observables
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Generating Surface Currents
Use Component View to post-process data, then
view with SmartView
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Visualizing Surface Currents
(Currents are color-coded according to their
intensity.)
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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.
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Visualizing Contours of Fields

• Rendered with AEs SmartView.
• Viewing contours from above.
• Vehicle forward direction is x axis.
• YZ-plane is vehicles front face
• Contour is taken at z 2 m
• Color scale units are in Volts/meter

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Generating IsoSurface Contours
This map generates two surface and combines them
with the vehicle
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Visualizing IsoContour Surfaces
2 V/m surface
5 V/m surface
(Front of contours removed for clarity)
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Using Light to Enhance the View
(Previous figure viewed from below)
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Combining Contours with IsoSurfaces (color
mapped)
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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