[SOLVED] Simulation of a microstrip line

[Sravan1541]

Hello guys,
I am designing a micro-strip line for 2.4 GHz in HFSS. I have found the trace width for 50 Ohm using the impedance calculator. I wanted to verify through simulation. I used waveports on both ends. And when I look into the S11, I can see that it increases with frequency and its below 20 dB. That's fine, but when I look into Z11, the real part is not 50 Ohm, and varies with frequency ? Can someone explain me if the way i am looking at the line impedance coorect ?

 

[volker@muehlhaus]

By definition, Z11 is the input impedance with all other ports open. So with Z11, you are looking into the open ended line.

 

[Sravan1541]

So how can I be able to find the exact line impedance or see if the impedance is matched ?

 

[PlanarMetamaterials]

You can derive the input impedance from S11 (which assumes all other ports matched).

Alternatively, in HFSS, you can simply look at the modal impedance, Zo(1) or Zo(2).