The Feko Lite edition has a triangle limit of 300. This makes it impossible to simulate big structures like trees at X-band. I can probably just scrape by some wheat leaves. The approach so far has been to produce a few level of branching with ngPlant and saving this to lightwave obj. NgPlant is an opensource specialized tool for plant modelling using parameters such as declination, phototropism, order of symmetry etc.
I made a very very small spiky tree to test integration with Feko Lite. The obj model was converted to STL mesh with Blender. Using blender with ngPlant also allows creating optical renders of the scenes being simulated.
Feko handles the simple model well enough. I did some plane wave simulation to estimate RCS. Then I can look into SAR image synthesis.