s11 and s22 graph result

[Numan154]

how i know from s11 and s22 graph that hows my design ?? how i make conclusion from it ....what r the points ??

 

[RCinFLA]

You have be a little more specific. S11 and S22 are just input and output impedances. Magnitude plots of each would be return loss. This is how close the impedance is to the S parameter transmission line impedance. -20 db return loss is a close impedance match. It represents a small circle at radius = 0.1 around the center of a Smith chart.

 

[Ow@i$]

they simply represents reflection back... e.g.
if S11=-10db
or 10Log(a/b)=-10db (where a is port 1 and b is port 2 of any circuit..( Twoport network) )
log(a/b)=-1
taking antilog....
a/b=0.1
or a=b/10

means if you insert a signal in port a.... 1/10th part will refelect back andremaing 9/10 part will be transferred forward.So they simply tell you behaviour of you circuit.
Kindly study : https://en.wikipedia.org/wiki/Scattering_parameters

 

[natnoraa]

if you want a simple and straightforward answer, that is if your S11 and S22 are below -10dB, you can probably send for fabrication. all the more better to tune them to less than -20dB. they basically tell you that you have good input and output matching to 50 ohm ports (i assume they are 50 ohm).

 

[N.Narayanan]

S11 is refelected input power and s22 is reflected output power.
In magnitude, we can say input return loss and output return loss.

Explanation for your query with example:
Assuem your passband is 500MHz to 600MHz, Impedance of your syatem is 50 ohm
Case 1: If return loss of S11 is 20dB in the band of 500MHz-600MHz, then max power (approx) transfer from input to ouput and vice versa.
Case 2: If return loss is less than 20dB in the band of 500MHz-600MHz, then less power transfer from input to output than case 1 ans so on..

Note: Outband of band no return loss available.

If you have still doubt, tell me your device (like amplifier, filter and etc..) and I will tell you more information.