UTD (Polygonal and Cylindrical)

With this option the UTD parameters for UTD polygons and cylinders are specified.

Parameters:

Max no. of ray interactions

This parameter gives the maximal number of ray-interactions (that is reflection and diffraction combined). If for example, the parameter is set to 3, a ray can have 3 reflections, or 2 reflections and a diffraction. If set to 0, only direct rays are taken into account.

Write debug information to *.dbg

If this item is checked a debug file (extension .dbg) is generated. It contains large amounts of information and should only be used when debugging.

Write ray data to

*.bof file (default)

This option exports the rays during the UTD solution process to the .bof file for visualisation in POSTFEKO.

*.ray file

This option exports the rays during the UTD solution process to a .ray file. This text file can be used for custom post-processing.

Note:

Large .ray files are possible when the MoM and UTD solution have not been decoupled and the MoM part contains a large number of mesh elements.
For parallel runs the run-time can also increase significantly when exporting ray data.

The following abbreviations are used in the .ray file and POSTFEKO:

·: Creeping wave intermediate point on geometry surface
B: Diffraction at an edge
D: Diffraction at a corner or a tip
E: Diffraction at a corner (of an edge)
K: Diffraction at a wedge
Q: Source point
R: Reflection
S: Observation point
C: Creeping wave attaching and shedding point on geometry surface
V: Reflection at the shadow boundary of a creeping wave

Ray contributions

Determines which ray contributions to take into account.

Direct and reflected: Direct and reflected rays are taken into account.
Edge and wedge diffractions: Diffraction on edges and wedges are taken into account. The ray may include an arbitrary number of reflections, but only one diffraction. The total number of interactions (the number of reflections plus one) for the diffraction may not be larger than specified in Max no. of ray interactions.
Corner diffraction: Corner diffraction
Double diffraction: Double diffraction on edges and wedges and combinations of reflections are taken into account. Single diffraction rays are not included in this item.
Creeping waves: Creeping waves on curved surfaces.
Cone tip diffraction: Tip diffraction at the tip of a cone.

Uncoupled with moment method

This item specifies whether the coupling from the UTD region to the MoM region should be considered. This option should only be used when the UTD and MoM regions do not couple (interact) strongly.

Increasing the type and number of ray interactions increases accuracy and the computation time. The user should therefore make a compromise between the number of ray interactions and the ray contributions. Choices made in this card should be made on physical considerations to get optimal use from the UTD formulation.

The following restrictions apply for the hybrid MoM/UTD:

No dielectric bodies or dielectric ground.
Only flat polygonal plates or a single cylinder allowed in the UTD region.
The structure types can be PEC or of lossy metals, and the PEC structures can have coatings and thin dielectric sheets.
UTD and PO are not allowed to be used simultaneously in a model.