Grounded coplanar waveguide

[jmb22]

Hi,

I am trying to get simulation of the magnetic field behaviour for a grounded coplanar waveguide. I am using HFSS for 3 days now. And my only success has been to install the software.
Basically, I designed the GCPW using 2 wave ports. However, I can't get an output that makes sense. I calculated the width and gap to get impedance match to 50Ohms using TXLine.
First, how do you define the 3 ground planes as "ground plane". Basically, they are not really plane but rather box so I can't use the option of HFSS.

I am not interested to generate specific mode in GCPW except a quasi TEM mode. I am planning to use the GCPW as a broadband transmission line (5GHz to 40GHz)

Second: should I define any mesh operations?

Also, if the rectangle that defines the Wave ports are such that they are connecting the central line, the 2 ground planes on top of the substrate and the ground plane on the bottom, then I obtained the follwoing:

[error] Port refinement, process abc3d died unexpectedly.

My question: WHY?

If I adjust the ports so they are only connected to the top metallic layers, then it "works": no error message.
However, the direction of H field lines and the amplitude do not make sense?

Thanx for your help.

 

[harmony]

look man,
ur case is some how complicated, as u cant define ur wave guide as a (grounded ) CPW, but rather a (Microstrip) !
I've done some similar work in my master b4 like urs, and the best to simulate such structure is to consider it a microstrip or a sort of mixed tx-lines.
have u ever used SONNET ?
try it, it might b helpful 4 ur case
Goodluck !

 

[rugbyfun]

Hi,
when you draw an object you can assign
Perfect conductor to it.

HFSS will consider it a s perfect conductor not as a ground since perfect ground does'not exisit in reality....
and in any case you do not need a perfect ground to create a CPW
exitation.

If you have a legal copy of HFSS and you cannot obtain
a results in 4 day I would strongly suggest
to contact the customer service of Ansoft in your area
you certenely wil get an answer and all the training material for
your application

Rugbyfun