EM simulation

Hello me_forouzan!

An EM simulation is for "ElectroMagnetic simulation" and it could be defined as a software (tool) for solving any EM problem like, solving antenna fields and behaviour, RF (radio frequency) and MW (micro wave) devices and other scattering/reflecting issues with EM waves!

Regarding your 2nd questions; It's depends!
If you would like to solve a 2D (two dimensions) RF curcuits you will have SONNET, IE3D, MOMENTUM etc.. if you want to solve the full 3D model you should use CST, HFSS, FEKO etc. - the best simulation tool will depends on the specific application and design.
The software vendors claim that their tool is accurate with in almost 100% of EM problems!
But you have to evaluate each one accordingly to your application, as told before!

Good Luck!
IH

I used two transformer in my circuit. Is it necessary that i have EM simulation in my simulations?

Hi,

I think you don't need an EM solving.
Particulary if you are having discrete RF transformer.

And you don't need it at all if these transmformers are in DC circuit (no RF invloved)!

IH

I used transformer for designing one ultra wide band LNA (in RF part of circuit). Is it necassary that i use EM simulation?

i think it is. You can use sonnet