|
Fig. 1. XETS antenna (pictures
taken from [1]) |
Fig. 2. WIPL-D Pro CAD model
after import |
Antenna geometry description (Fig. 1),
obtained in the form of a STEP file and measured results were obtained
from the authors of papers [1,2].
After import, the inside structure of the model (Fig. 2) can be
investigated by using cutting planes, or transparency/hide commands over
parts of the model (Fig. 3).
By using only one boolean union operation, we turn the whole model into
a single body ready for material assignment and meshing. In fact, it is
necessary to assign materials on just two regions (substrate and coaxial
line dielectric) which is done by a few mouse-clicks (Figs 4-5). All the
faces in the model automatically adjust their material specification
according to the regions they belong to.
|
Fig. 3. Investigating the inside
of the model |
Fig.4. Domain assignment to
substrate |
There are two meshing algorithms
available in the program. For this model, we used uniform meshing
algorithm and specified local mesh size on parts of the model where this
is needed (Fig. 6). The coaxial feed is made of three coaxial surfaces
very close to each other so the mesh needs to be fine in this part to
follow the geometry precisely. The automatic meshing process takes about
30 seconds, and results in an excellent all-quad mesh (Figs 7-9).
Automatic mesh algorithm of WIPL-D Pro
CAD is very fast, controllable and can be used to approximate very
complex geometries. The usage of the mesher is quite easy since there is
only a few control parameters to adjust. On the other hand, vast
majority of models can be meshed with default parameters, at first-pass.
|
Fig. 5. Model after domains
assignment, cyan – metallic, red –dielectric surfaces |
Fig. 6. Setting local mesh size |
|
Fig. 7. All-quad mesh of XETS
model |
Fig. 8. Feeding part mesh (zoom
in) |
Fig. 9. Upper side of substrate mesh
(zoom in)
Simulation Results
The antenna has been simulated according to instructions from [1].
The results for VSWR (Fig. 10) show excellent agreement with the
measured results, in the range of interest – intended application
(3.1-10.6 GHz).
The radiation pattern has been calculated at 4 GHz and displayed in Fig.
11. The diagram is centered around theta=90°, since it corresponds to
measurement results around theta=0° (due to different spherical
coordinate systems). In this case as well, we can see the excellent
agreement between simulated and measured results.
|
Fig. 10. VSWR overlay in range
2.5-11.5 GHz |
Fig. 11. |E| [dB] in E plane 4
GHz |
References
[1] Jorge R. Costa, Carla R. Medeiros, and Carlos A. Fernandes, “Compact
Printed Tapered Slot Antenna for UWB,” 3rd European Conference on
Antennas & Propagation – EuCAP, Berlin, Germany, March 2009.
[2] Jorge R. Costa, Carla R. Medeiros, and Carlos A. Fernandes,
“Performance of a Crossed Exponentially Tapered Slot Antenna for UWB
Systems,” IEEE Transactions on Antennas and Propagation, Vol. 57, No. 5,
pp. 1345-1352, May 2009.
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