I have designed lna and simulate it using ads2003a .I have simulate it using s parmeter simulation and find out the gain ,noise figure ,vswr,stability.Is it enough to simulate only by s parameter simulation and check out my parameter or anyelse simulation such as harmonic balance etc. is also necessary.the frequency range is s band.
Using the parameters that you stated should be more than enough for designing a LNA. However, you should also take care of what are the critical points that could affect your parameters as there bound to be tolerance in the pcb fabrication, in which the experimental results might varies a lot compared to your simulated reuslts.
You must take into account the linearity of the LNA. As someone already said, you need the non-linear model of the transistor to do this in harmonic balance. As a minimum you should do the calculations by hand. For example, if you designed a LNA for a cellular phone handset and didn't consider the linearity, the phone wouldn't pass specifications and it would fail in the field when in a strong signal environment.