coplanar waveguide hfss

In Ansoft HFSS simulation software I build a Coplanar waveguide. In a Coplanar waveguide you put a signal on the central conductor, and you ground the other two conductors. But how can I ground those conductors in HFSS ?

I remember someone posted a tutorial on this topic, u can try look at
https://www.edaboard.com/viewtopic.p...&highlight=cpw

The rules are strict when it comes to CPW structures in HFSS. You have to maintain a certain width and length ratio, depending on the size of your lines and your dielectric. If you want, I can post those rules, but I have to dig them out first.

First, you need to create a radiation box for your CPW. The box should extend down below the substrate. Then you can make the rectangular port a little bit lower than the substrate. There is a rule of thumb to have the port height at least 4 times the substrate thickness. This is not really necessary. What you can do is first to have the port height 4 times the substrate. And then try to plot in logarithmic scale the magnitude of E field. You will see that the hottest area is between the signal line and the ground plane. If the difference between the hottest area and the collest area (top of the port) already something bigger than 1e4, you may reduce the height of the port. This will give you a better accuracy for the port.

you can define a rectangular box to include the cross section of CPW structure and substrate first, then use boolean operation to substrate 2 smaller rectangles to get a polygen having contact with the ground layer.

I am not very clear.
Is the port are lump gap source or wave port?
How do I set the terminal line to wchic ground?
:(
ecoh

Pls refer wlcsp's post about the size of the wave port.
Schematic illustration of wave port of CPW is attached.
Best Regards.

For lump port excitation, you need to draw a strip to merge the two grounds and signal line together. Then a lump port can be assigned on the signal line infront of the strip.

Hi,

Attached are port tutorials for your reference. I believe the second one which talks about CPW port is especially useful for you and should be able to clear your doubts and address your issues. It has details on how to set up the grounded/ungrounded/partially grounded CPW in HFSS and their applications.

good one-helped me a lot. I was so wrong!

I have the same problem, but haven't enough points, can anbody kindly help me?

thanks!

the width and length of wave port have an effect on impedance of cpw,how should u consider this?

can somebody help?

so few people?

Width and the height of the waveport definitely affect the impedance. If I remember right, the ground rules are
1. width of the waveport should be 5 times the g/s/g and
2. height should be 4 times the substrate's height.

Of course, the integration line can be drawn either from the signal to ground line or the other way. I also found that one integration line on either side is enough.

Remember, these are ground rules which work most of the time but you should always verify the port simulation in HFSS before you incorporate these structures for an actual structure simulation.

The best tutorials are in the topic if you have doubts.

Hope this helps.
Ananth.

Directions from the file:

Wave Port Size
The standard recommendation for most CPW wave ports is a rectangular aperture
Port width should be no less than 3 x the overall CPW width, or 3 x (2g + w)
Port height should be no less than 4 x the dielectric height, or 4h
If no convenient ?solid face(s)? meet the above sizing requirements, draw a 2D rectangle for the Port.

Wave Port Location
The wave port should be centered horizontally on the CPW trace
If the port is on GCPW, the port bottom edge should lie on the substrate bottom ground plane
If the port is on ungrounded CPW, the port height should be roughly centered on the CPW metal layer

Wave Port Restrictions
As with all wave ports, there must be only one surface normal exposed to the field volume
Port should be on exterior model face, or capped by a perfect conductor block if internal
The wave port outline must contact the side grounds (all CPWs) and bottom ground (GCPW)
The wave port size should not exceed lambda/2 in any dimension, to avoid permitting a rectangular waveguide modal excitation

Added after 5 minutes:

A better idea. Here's the file, compressed to 456k (that should be small enough right?)

It's a nice answer for me! Appreciate so much!:D

excellent reply!

Added after 1 minutes:

i really dun understand why it always needs points to download!

you should use lumped port fo excitation.
only excite the port in hfss that you want to realy excite!

a lot of thanks

Added after 4 hours 13 minutes:

can someone share a project file for this setup?
your noble deeds could benefit a lot of guys who are not familiar with HFSS.