100% this. When I startup-ed, I looked hard for a free alternative for RF simulation. There's some FDTD solvers, but as mentioned, they require you to spec the

100% this. When I startup-ed, I looked hard for a free alternative for RF simulation. There's some FDTD solvers, but as mentioned, they require you to spec the mesh, which is laborious and black magic which Ansys HFSS simply does for you. Only saving grace is that these companies usually have some "start-up" discount (~95% discount), which of course I anticipate feeds the lack of open source development.