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This article demonstrates the application
of WIPL-D Pro to the simulation of electrically large automotive
structures.
WIPL-D is ideal for such applications for
two reasons:
• The geometry can be easily imported from different CAD formats, and
edited using the powerful user interface,
• Due to higher order polynomial basis functions, large structures are
simulated very quickly.
The model used here was made manually, instead of being imported from
some CAD file. We have simulated placement of two antennas at two
different frequencies:
• Microstrip patch antenna at 2.5GHz (could be used as GPS antenna),
• Monopole antenna at 900MHz (GSM antenna).
Both antennas are mounted on the roof of the car. Because of symmetry of
the model we have used one symmetry plane. Real ground is modeled as
PEC. Results of our interest are radiation pattern and near field inside
the car.
WIPL-D Modeling
The first step is modeling of the structure in WIPL-D Pro. In the
example that is shown in this paper, we used WIPL-D Pro 3D modeler
(based on using parameterized objects, quad plates and wires as building
blocks). As a result, obtained mesh is an optimum one and minimizes
memory usage and simulation time.
Model of the car is shown in Fig 1. One
symmetry plane and PEC plane are used, so only one half of the car is
modeled. Model of the patch antenna that is added to the model of the
car is shown in Fig 2. As we can see, it is a circular patch
coupling-fed by a microstrip line. Antenna mounting areas for two cases
(monopole antenna and patch antenna) are shown in Figs 3 and 4.
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Figure1. Model of the car. |
Figure 2. Patch antenna. |
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Figure 3. Monopole antenna on car
roof. |
Figure 4. Microstrip patch
antenna on car roof. |
Simulation Results
Operation frequency is 900MHz for the model with monopole antenna, and
2.5GHz for the model with patch antenna. Direct in-core solver is used
for the model with monopole, and for model with patch antenna we have
used the out-of-core solver. Computer used for these simulations is
Intel(R) Core(TM)2 Quad CPU, 2.83 GHz , 4 GB of RAM. Number of unknowns,
memory requirements, and simulation time of analysis are given in Tab.
1.
Table 1. Analysis characteristics
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Model (Antenna) |
No. of unknowns |
Memory used [GB] |
Simulation Time [min] |
|
Monopole |
5556 |
0.242 |
1 |
|
Patch |
42171 |
3.5 GB (42.3 GB hard disk space) |
120 |
Radiation patterns of monopole and patch
antenna on car roof are shown in Figs 5 and 6. The second parameter of
interest is near field inside the car and in the surrounding area. Near
field is calculated in the symmetry plane (Figs 7 and 8). Although near
fields are low inside the car in both cases, they are lower when patch
is used due to main-lobe orientation.
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Figure 5. Radiation pattern of
monopole antenna. |
Figure 6. Radiation pattern of
patch antenna. |
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Figure 7. Near field for monopole
antenna. |
Figure 8. Near field for patch
antenna |
Conclusion
Based on presented, the simulation time is relatively short, and we
haven’t used adaptive order reduction in these examples, which is a
powerful technique that could further speed-up simulation and eliminate
the need for the out-of-core solver. So, we can conclude that WIPL-D
software can be efficiently used for simulation of electrically large
automotive structures.
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