compare HFSS and Fidelity

hfss is finite element method and fidelity is full wave method.
hfss is better than fidelity.

Actually, HFSS is a frequency domain full 3D EM analysis tool, based on the Finite Element Method (FEM).

Fidelity is a time domain full 3D EM analysis tool, based on the Finite Difference Time Domain (FDTD) technique.

Each has its relative strengths and weaknesses, so which tool is best really depends on your application and preferences. No one can say that one is better for all applications. Some problems are more efficiently solved in the frequency domain, others are more efficiently solved in the time domain.

--Max

which one is better Fidelity or CST would be a better question

Personally, I dislike such questions because "which one is best" depends on so many factors. Just a few are:
- What is your application? (Biggest question, in my opinion)
- What is your error budget or tolerance?
- What is your budget? (The one your boss cares about.)
- What other design tools does it have to work with?
- What EM simulation technology are you comfortable with, and understand?

This is just a few of the questions. When you are a graduate student, you usually only worry about the first one and the last one. When you get a job as a design engineer, the questions in between become a lot more important to you.

--Max

Agilent Momentum & EMDS are good EM tools

I fully agree with Max.

what are your criteria and objectives.
for Time domain solution u have choice between CST (FDTD) and MicroStripes (TLM)
good luck

Hfss if s high frequency structor simulator ,basically in frequency domain and fielity is in time domain so there is no question in comparison between the two,and if we do the comparison then u shoul state on which factors