UTD (Polygonal and Cylindrical)

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



Figure 1. The UT - Specify the UTD/RL-GO parameters dialog, set to UTD (polygonal and cylindrical).

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.
Export ray file for post-processing
When this item is checked the ray information is exported to the .bof and .ray files. Activate this option if ray paths are to be displayed in POSTFEKO where the ray information is read from the .bof file. The exported ray information may result in a large .ray file and a dramatic increase in the .bof file size. 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
  • 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.