Re: Machting network
thanks.. using S11 paramter seems easier to me..
i'm a very slow learner
so pl bear with me.
so the thing is:
i checked S11 parameters.. the problem is this:
The central frequency shifts when i change the dielectric constant.
For eg. original structure: er=2.33, central freq = 14.8GHz (it goes below -10dB)
bandwidth = 0.3230 GHz (i have taken the difference between the points where the S11 curve crosses -10db on the 2 sides of the central freq, ie S11 curve crosses -10dB at 14.63GHz then reaches a max. at 14.8GHz and then again crosses the -10bd at 14.96 GHz)
Now.. i change the dielectric constant to er = 2.1
Then, i simulate using IE3D.
I observe that central freq has shifted to 15.6 GHz. (it goes below -10dB... at 15.41GHz and 15.79GHz)
bandwidth for this case = 0.3783 (difference between 15.79 and 15.41)
1. Since central freq has shifted from 14.8 to 15.6 GHz... I'm not sure if i can say this antenna system is matched properly or not.. or can I ? can u explain..
2. However, if i consider this er=2.1 and 15.6Ghz as a new antenna system (and neglect the original design with er=2.33 and 14.8GHz).. this means that the antenna is matched .. right ? because S11 parameter goes below -10db value..
So i can say that if er=2.1 and operating freq is 15.6 GHz then the antenna is properly matched to 50ohm feedline. Am i correct saying this ?
3. But if i consider that 14.8 GHz should be the only operating freq,, then this shift of 14.8 to 15.6 makes the input impedance mismatched for the new antenna (With er=2.1) because instead of operating at 14.8GHz it is operating at 15.6 GHZ right ?
So does it mean my antenna is mismatched ?