Broadband Antennas

Crossed Exponentially Tapered Slots Antenna

Vivaldi
Antenna

Ultra Wide Band
Elliptical Antenna

Crossed Exponentially Tapered Slots Antenna (XETS)

CAD Model Import and Simulation


Fig. 1. XETS antenna (pictures taken from [1])

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. 2. WIPL-D Pro CAD model after import


Fig. 3. Investigating the inside of the model


Fig.4. Domain assignment to substrate


Fig. 5. Model after domains assignment,
cyan - metallic, red - dielectric surfaces

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. 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.

PDF application note

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