RL-GO Settings

A number of optional settings are available when using ray launching geometrical optics (RL-GO) to solve parts of the model.

On the Solve/Run tab, in the Solution Settings group, click the  Solver Settings icon. On the Solver Settings dialog, click the High frequency tab.

Decouple from MoM solutions

This option ignores the RL-GO regions when calculating the MoM currents. The runtime and memory will be less compared to a fully coupled (default) solution. This option should be used with caution. For example, the input impedance of a dipole antenna close to a dielectric sphere, where the dipole is solved using the MoM and the sphere using RL-GO, will (incorrectly) be the same as that of the MoM dipole in free space.

Tip: Use this option where the MoM and RL-GO regions are electrically far apart (for example an aircraft nose cone radome).

Maximum number of ray interactions

This option limits the number of ray interactions (reflection and diffraction combined). For example, if this parameter is set to 3, a ray can have three reflections, or two reflections and a transmission. If left empty, then the maximum number if ray interactions is determined automatically.

Edge and wedge diffractions

This option takes the diffraction on edges and wedges into account.

Export ray file for post-processing

This option exports the rays during the RL-GO solution process to a .ray file. The ray-tracing information is also stored in the .bof file and you can view the rays in POSTFEKO.

Note: Large .ray files are possible when the MoM and RL-GO solution have not been decoupled and the MoM region contains a large number of mesh elements.

Adaptive ray launching settings

This option allows you to control the density of the rays launched, as well as when to stop tracing a ray based on the ray's decay.

• High (more rays): The ray density is high. Results take longer to obtain but with higher accuracy.
• Normal (default): The default ray density setting.
• Low (fewer rays): The ray density is low. Results are fast to obtain but with lower accuracy.
  Tip: Start with Low (fewer rays) which uses the least computational resources. When the model appears to be performing as expected, use a higher setting.

Fixed grid increments

This option allows you to specify the angular or spatial resolution for ray launching. The resolution is specified by means of the increments in the U direction and V direction for a parallel ray front (plane wave source) or in the φ and ϑ directions (sources other than plane waves). Though the run-time for a problem involving RL-GO may be decreased using this option, it may influence the accuracy of the solution.

Note: Manual specification of the increments should only be used after the implications have been carefully considered.