OpenEMS is a free FDTD (Finite Difference Time Domain) simulator suitable for a wide range of computational EM problems. There's definitely a demand for a modern 3D CAD type frontend, if anyone's looking for a weekend project. There are a few graphical interfaces available (4NEC2 is the most popular free one) but they are all pretty old. It's a command line program that takes a text file input, where each line of text represents an 80 column punched card in a card stack. It was originally written in the 1970s at Lawrence Livermore National Lab, so the interface leaves much to be desired. A quick summary of the options that *are* free: NEC-2 is a public domain Method-of-Moments (MoM) simulator suitable mainly for wire antennas and some planar antennas which do not rely on dielectric structures (so no patch antenna simulations). It's getting to the point where I'm seriously considering writing my own FDTD engine. Quote from: Kelbit on January 23, 2016, 09:10:25 am I have been searching for a good free 3D field simulator for a while.

Cst antenna simulation