why i have different answers

why i have different answers
i have used three programs in order to get gain and impedance (MANAMA,PCAAD,4NEC2) i have give the same parameters but each program give me different answers why i cant understand as i know these programs uses the same method (MoM) and i want to ask how does MoM operates (how does it work ..i need information about MoM

Please show your model, show results, show difference. What is your reference?

Different simulation packages based on the same method might require specific model preparation actually. Something must be wrong with the models. Have you tested convergence of results - decreasing mesh-size of the structure and controlling results change?

Here is MIT notes on Method of Moments. I hope it helps.

thanks for the fil but i hope i can get more simple answers

What do you mean by "different answers"? For example, is the difference in gain 10 dB, 1 dB, 0.1 dB or 0.01 dB or what? You have to be more specific.

no i mean i put the same parameters but when i use differnt softwares it gives differnt answers you can see the file that i have add it

Where is file you mentioned?