With this option the RL-GO parameters are specified.

Figure 1. The UT - Specify the UTD/RL-GO parameters dialog, set to RL-GO.


Use RL-GO on all surfaces with label
The label to which the RL-GO should be applied
(optionally) up to label
The label up to which the RL-GO should be applied. RL-GO will not be applied to labels outside of the range between this field and the label in the previous field.
Max no. of ray interactions
This parameter gives the maximum number of ray-interactions (that is reflection and transmission combined). If for example, the parameter is set to 3, a ray can have 3 reflections, or 2 reflections and a transmission. If left empty, then the maximum number of ray interactions is determined automatically.
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.
Source point
Observation point
Transmission on a dielectric
Ray contributions (higher order)
Determines which ray contributions to take into account.
Edge and wedge diffractions
Diffraction on edges and wedges are taken into account.
Set face absorbing properties
This option enables the specification of the absorbing and reflection/transmission properties of the faces with regards to rays. For both sides of a face (normal side / opposite to normal side), the following options are supported:
  • Consider transmission / reflection of rays from the face(s).
  • No transmission / reflection of rays from the face(s).
Ray launching settings
Specify the settings for the launching of rays.
Adaptive ray launching
The ray launching parameters are determined automatically during the solution process.
Fixed grid increment
The Angular increment (theta / phi) and the Spatial increment (distance between the individual rays in the parallel ray front) for the ray launching are specified by the user.
Adaptive ray launching accuracy
Controls the density of the rays launched as well as when to stop tracing a ray based on the ray's decay. Choose between High (more rays), Normal (default) and Low (fewer rays).
Tip: Start with Low (fewer rays), which uses the least computational resources, and when the model appears to be performing roughly as expected, use a higher setting.
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.
The main advantages of RL-GO are as follows:
  • It is suitable for large arbitrarily shaped objects (also curved objects).
  • Dielectrics are supported.
  • A plane wave source required for the calculation of far field RCS is supported (the UTD has a problem with caustics).
  • Multiple reflections can be solved more efficiently than UTD or PO.
When no UT card is used, the following default values apply:
  • Max no. of ray interactions: 3
  • Write debug information to *.dbg: unchecked
  • Export ray data for post-processing: unchecked
  • Select ray contributions includes:
    • Direct and reflected
    • Edge and wedge diffracted rays
    • Corner diffraction