Please some one help me out. i m getting such attached graph of s-parameter at resonant frequency of 10GHz. please help me out which parameter should i change in cst so that i can get good result of s-parameter.
thank you
Ur Structure is resonating well for 10 GHz but its bandwidth is High. If u want High Q structure then modifications are to be done but its all depending on ur application. FR4 is a lossy Material. Try giving the value of its loss tangent and simulate the structure again..!! Also, If its a 2 port device, see that ur structure is symmetric..!!
To me, it looks like you have some other parts resonating near 10GHz, you might need a look of the snapshot and check where in your structure is causing that. To me your 10GHz Q factor is high enough, you almost reached -38 dB. Thus improving resonance at 10GHz has little room, but removing other resonance near 10GHz might be a worth try.
Loss tangent or Tan(D) is a measure of How much losses a dielectric can add..!! For FR4 the loss tangent is 0.027 typically..!! So ur Structure is an Planar Antenna ?? Which software are u using to model it ??