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Grounded coplanar waveguide with HFSS

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jmb22

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hfss coplanar waveguide

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.
 

haydar

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coplanar waveguide hfss

jmb22 said:
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.


1- one of my friend (wlcsp) suggested to avoid an aspect ratios(length:thickness) of more than 1000:1. you use length:thickness=>4mm:200nm=>20000:1
Instead, use 2D shapes.

2- calculations do not match experimental results. I calculated microstrip width by using dielectric constant and width of the substrate, however it did not work as I expected. I simulated it with hfss, I obtained the same result with my design. than by changing parameters, I got the exact result.
therefore, do not count on calculations.

3- although I am not sure, you should define transmissionline as radiation boundary.
 

asdfaaa

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hfss coplanr waveguide simulation

jmb22 said:
Hi,
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?

quote]

About the ports setting of CPW, you can find a lot of introductory materials in this forum. For GCPW, the rectangular port need touch the lower-layer ground metal plane. You are using waveport, and some errors occured, I think the problem may come from the width of the port is too big, and also I strongly recommend that you can define the integration line which is parallel with the lower-layer ground plane at the gap.

About the mesh refine, since you are interested in the quasi-TEM mode only, no consideration of the higher mode, and you treat it as general transimission line, so your interest is just the characteristic impedance Z0, am I correct? In this case, you dont need a huge ground plane and huge computational domain, so no need to do mesh refinement.

I didnt read ur model yet, about just the general information.

Best Regards,
 
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