OS-E: 5010 High Frequency Electromagnetic and Thermal Analysis of Antenna

Demonstrates Feko and OptiStruct coupling through an analyze of an antenna model for radiation and heat transfer.



Figure 1. Geometry of Pin Fed Patch Antenna and FE Model
Table 1. Solution Sequence for Feko-OptiStruct Analysis
Steps Output
The .epl and .nas files are obtained using EG (End of Geometry) from EDITFEKO.  
Add the update.py file to the Compose Installation directory in your machine (example: C:\Program Files\Altair\20xx\Compose20xx.y).
Run the .oml file in Compose and input the files generated by Feko in the toolbar that appears as:
  • For Nastran Input file: Antenna.nas
  • For Heat power file: Antenna.epl
  • For Map file: Antenna.map
  • For Nastran output file: Specify a user-defined name for the output file (In this example, Antenna2.nas is specified as the name of the output file).
 Compose will write a new .nas file and the heat-loss_2P93000000E009.fem file.
Open OptiStruct and input the above generated Antenna2.nas file and perform Heat Transfer Analysis. Results in heat lose, due to radiation from antenna.

Model Files

Before you begin, copy the file(s) used in this example to your working directory.
Feko files
Antenna.epl and Antenna.nas
Compose file
map.oml
Map file
Antenna.map
Python Script
update.py
OptiStruct files
Antenna2.nas and heat-loss_2P93000000E009.fem (these files can be generated by running the map.oml file in Compose)

Model Description

The objective is to compute the electromagnetic radiation pattern of the antenna in Feko and to analyze the heat generated, due to electromagnetism in OptiStruct. Altair Compose Script is utilized to modulate the Feko results and fed input to OptiStruct.

The device used (Figure 1) is a Pin-fed Patch Antenna comprised of metal patch, dielectric material connected to metal ground and surrounded by air. The patch is fed by a finite-element line port between the ground and the patch.

The input frequency is 2.93 GHz and the source power is 30 W. Of the 30 W, 3.2 W is reflected to the source (mismatch loss), 21.5 W is radiated, 1.7 W is lost in the metallic faces and 3.6 W is lost in the substrate. The last two electromagnetic losses are transformed into heat. This heat loss is analyzed in OptiStruct.

Antenna Electromagnetic Properties (Feko model details for reference)
Substrate
Value
Relative Dielectric Permittivity
2.2
Loss Tangent
0.01
Size
7 x 10 x 0.287 cm3
Metal Patch
Value
Relative Dielectric Permittivity
2.2
Electric Conductivity
1E+06 S/m
Size
3.118 x 4.665 cm2
Thickness
35E-06 m
Ground
Value
Electric Conductivity
1E+06 S/m
Thickness
35E-06 m
FE model (OptiStruct model details for Thermal Analysis)
Element Type
CTETRA4
Material: Copper (MAT4)
Thermal Conductivity
401.0 (W/m)-K
Specified Heat Capacity
385 (J/kg)-K
Density
8960 kg/m3
Free Convection Heat Transfer Coefficient
25.0 W/m2
Material: Dielectric (MAT4)
Thermal Conductivity
0.3 (W/m)-K
Specified Heat Capacity
300 (J/kg)-K
Density
1000 kg/m3
Free Convection Heat Transfer Coefficient
20.0 W/m2

Results



Figure 2. Antenna's Far-field Radiation Pattern


Figure 3. Surface Currents in the Metals


Figure 4. Final Temperature Distribution