which tools is mostly used for electromagnetic field simulat

which tools is mostly used for electromagnetic field simulation in industry?
which tools is easily available (free or demo version) used for electromagnetic field simulation to learn practical basic concepts of EMF?

Maxwell and CST are qualified for field simulation, although never used before

HFSS, CST MWS, ADS/Momentum, COMSOL Multiphysics, FEKO are all very common in industry and very expensive. You probably cannot get even a demo for free or even cheap, these are very expensive but also very useful and powerful.

I'm not too sure about free ones. MIT makes a free FDTD (called Meep) that is open source so you can modify it. I've seen it used a lot in academia but dunno about industry.