Re: what is MOM and FEM
When you studied your em-theory you probably solved everything analytically. However, real world problems cannot in general be solved this way. Instead we have to solve them numerically. This creates a new huge area of em, computational electromagnetics (CEM), also called Electromagnetic Modeling. As you know, all macroscopic electromagnetic phenomena is described by the Maxwell's equations. So with CEM we solve the Maxwell's equation numerically and this is what the em software like HFSS and NEC does. There are different methods to use, FEM, MoM and FDTD are the most common ones. There is no method which is perfect for all problems. As an example, HFSS uses the Finite Element Method (FEM). With this method we divide the structure into Finite Elements, most often some triangular structure. Then solve the equations for every corner point, that is, determine the fields there. It is important to understand the methods so that you know how to solve different problems efficiently. For more information I suggest you read some book about CEM.