PO and LE-PO Parameters

A number of optional parameters are available when using physical optics (PO) or large element physical optics (LE-PO) to solve a face or faces.

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.

Couple PO and MoM/MLFMM solutions (iterative technique): This option uses a hybrid iterative technique to determine coupling between the MoM or MLFMM region and the PO region.
Couple PO and MoM solutions (full coupling): This option takes into account the full coupling between the MoM region and PO regions. As a result, the currents in the PO region will have an effect on the current distribution in the MoM region.
Decouple PO and MoM solutions: This option ignores the PO regions when calculating the MoM currents. For example, the input impedance of a horn-fed parabolic reflector, where the horn is solved using the MoM and the reflector using PO, will be the same as that of the MoM horn in free space.
Tip: Where the MoM and PO regions are electrically far apart and far field quantities are of interest, decoupling the solution can reduce the memory and run-time without sacrificing the accuracy of the results.
Maximum number of iterations: This option limits the number of iterations for the iterative technique.
Stopping criterion for residuum: This option specifies the termination criterion for the normalised residue when using the iterative method. Terminate with convergence when the normalised residue is smaller than this value.
Store / reuse shadowing information: During calculations using the PO formulation, a large amount of the time is spent in determining which surfaces are illuminated from each source. This option saves the shadowing information to speed up subsequent runs. Re-use is only possible if the physical geometry of the model is unchanged.
Note: Storage of the shadowing information leads to large .sha files on disk.

Use symmetry in ray-tracing (when possible): This options allows symmetry to be used in full ray tracing when determining the shading to reduce run time. For geometrical symmetry, select this option to utilise symmetry. For electric and magnetic symmetry, this speedup is always used. It is possible, for example, to define half a plate and create the other half through geometric symmetry. An asymmetric object may then be placed in front of the plate. In this case, symmetry should not be used in the ray tracing.