# Tips for Using PO or LE-PO

Several tips are presented to reduce runtime and memory consumption when using hybrid methods involving the physical optics (PO) and large element physical optics (LE-PO).

• Decouple the MoM and PO parts if the coupling is negligible
If the interaction (coupling) between the MoM and PO parts are small, then the MoM and PO parts can be decoupled saving computational resources.
Note: It is recommended to always test this assumption by setting up a smaller model, for example, using a coarse mesh, specifying a single frequency and using a single source.
• Use special ray tracing options

For applicable models, set always illuminated or only illuminated from front to reduce the ray tracing time (for example, a reflector antenna).

• Minimize the number of MoM elements
If the coupling between the MoM and PO regions cannot be disabled, then reduce the computational resources by minimising the number of MoM elements (triangles/segments). Where possible use an equivalent source for the MoM part.
• Use LE-PO
The LE-PO can be used in areas where the geometry is smoothly varying and several wavelengths away from the source. The LE-PO surfaces can be meshed using a mesh size of up to $\mathrm{2\lambda }$ .