hfss tutorial cpw

Don't know about HFSS as I haven't sat down to learn it yet, but in momentum, and designer/ensemble, CPW is handled by defining an infinite ground plane and drawing slots for the gaps between the signal and gound traces. In momentum place the ports at the edges of the slots you just drew (you can enable edge & midpoint snaps to help with this) and then use the port editor to define them as coupled.

Alternatively, if you want a finite ground trace you could draw the ground-signal-ground traces on a regular trace layer, place six ports on the structure and, again using the port editor, define the two ports attached the signal trace as internal ports while setting the other four ports to be ground references for the signal ports in their respective planes. The simulator will give 2-port S-parameters with this setup.

I guess it would be possible to setup a finite ground cpw structure in designer/ensemble as well with a similar setup as momentum except that you can't define a ground reference for both ground traces. You can't setup ground reference at all in ensemble (stand alone product), as far as I know. I suppose that you can simulate the structure and take the 6-port data back into the circuit simulator and connect the ground ports together and use that node as the reference node for the signal port. Just spitballing here, haven't really tried this to see if it would work since I'm able to get what I want done between momentum and sonnet.

Iknow you didn't ask for the designer/ensemble information, but thought it might help anyone else reading the thread that had designer/ensemble instead of momentum, or at the very least start some healthy discussion. After all thats what these boards are for, right?

Hey,
Heres a tutorial on defining CPW's in HFSS.
Hope this helps.
Ananth.

Man, you rock!

Thanks a lot!!!

If you have more tutorials like this, please make us informed!

thanx a lot ananth. I feel the same way as pepino.
yeah if u have more like thie let us know ...

use Agilent momentum

With this file we can easy design wave port for CPW. However, in some cases, the distance between 2 CPW is to close, closer than the width of wave port. in that case, how can we excite CPW.
I tried to use lump port to excite cpw but the result is not good as using waveport.

Sorry for my question. I'm very new in HFSS world.

If I have substrate and CPW on top without ground. Then, I learnt from the above tutorial the dimensions needed for this case.

My questions:
1-How can I define the wave port ? Shall I draw rectange and assign it as wave port ? or how ?

2-and how shall I define the boundaries ? I'm using CST and put all as "open" ecept +z and -z "open add space". What should I do with HFSS??

Thanks in advance

Hey Abuantenna,
You were right when you said you just draw a rectangle and assign a waveport to it. Just be dure to define the integration line from the CPW to the ground plane. Obviously, the port is going to be perpendicular to the plane of the CPW and you know the approximate sizes of the edges of the port.
I had another suggestion. Before you hit the analyze button for the whole structure, do simulate the ports first and see if the port impedances are what you need in your structure.

I've never used CST and hence wouldn't know what you're talking about! :)

Ananth.

Added after 2 minutes:

Dear Thaihoa,
Its indeed a unique peoblem you're facing. Have you tried defining the waveports as suggested earlier with the ports overlapping in case of the CPW's being so close? Does it create a problem? I've never really faced such a problem but wud've definitely tried this before moving on to the lumped ports.

Ananth.

Thanks a lot.

I've got another question.
When I draw the phase results in rad., I can see the result between ±3.
My question: How I can draw between let say ±10 ??
So, to compensate for the phase response.

Hello,

I don't know how to see the attachments? It needs points? How can I get a point? I'm new to this forum and I don't know how to get points but I really need to know how to define a coplanar port in HFSS....

Thanks
Arash

Added after 12 minutes:

Agilent Momentum is very good, but it doesn't include metal losses for the coplanar transmission lines unfortunately.

Arsah

Added after 40 minutes:

I have tried ground-signal-ground. at port 1, my integration line was from gnd1 to signal, and at port2, my integration line was from gnd2 to signal. but the field lines in the solution for this mode seems to be from gnd1 to gnd2, i mean, they don't start from signal line. there should be another way...

Hello!

I'm new in this forum but I would be very interested in looking at the file port_tutorial_CPW.ppt which explains the design of the CPW in HFSS.If someone can send it to me to my e-mail, it would be greatly appreciated.

Thank you,
Carlos

thanks
use hfss 9

good pdf tutorial

what's the difference between v9 and v10

Anyone have any example projects/setups for doing CPW simulations in CST ?
I've tried with multipin port and I've simulated a simple cpw line but i don't know how to simulate 2 port in the same side (like the ports in a wilkinson coupler)

Thanks

I give you the CST project so you can help me on define the ports for this coplanar circuit in CST

Hi,

I need this CPW tutorial to simulate some CPW-based circuits with HFSS but i cannot download it as I dont have the required amount of points to check attachments.

Somebody knows if I can get it in the internet? or could you post it somewhere where I can access?

Thanks a lot

I am new in this forum. Could someone email me any example projects/setups for doing CPW simulations in HFSS ?

Thanks

Anyone have any example projects/setups for doing CPW in HFSS or Momentum ?
yes