Learning Forum

[Jason Huang]

Hello,

I would like to simulate a CPW (Ground-Signal-Ground) lambda/2 resonator on a substrate with large relative permittivity (~23000). I'm hoping to understand the S11 response (LogMag and Phase) in the frequency range of 1-200MHz, as the fundamental mode frequency should be ~ 35 MHz. The signal layer consists of a large contact pad (~200um, used for experimentally wire bonding) adiabetically tapered to a long meander line (~45mm in length). The width of the meander signal is ~30um, with a ~10um separation (dielectric gap) to the ground plane. I've defined a lumped terminal port sheet spanning across one side of the gaps from the edge of the contact pad to the edge of the ground plane as the excitation port for the simulation. The adaptive mesh is performed at 100MHz, and I've tried both interpolation and discrete sweeps. My question is:

1. Is the lumped terminal port the right way to set up the excitation for understanding the resonant behavior of the structure? I realize that to some degree, the shape of the port sheet could affect the simulated resonant response...
2. Should I change the adaptive mesh to compute at multiple different frequencies (the resonant frequencies?) instead of a single point, which is just the center of the sweep (100MHz)
3. Any general suggestions for improving the simulation accuracy are appreciated!

Thank you for the instructions. I'm willing to share more details of the simulation if there is anything else we should confirm.

 

 

 

[Takeshi Itadani]

1. Place a Lumped Port in the same way as when you actually excite the electromagnetic field on the structure. The brown rectangle in the image appears to be a Lumped Port, and if you plan to supply power to the actual structure by placing a probe or similar at that position, then using a Lumped Port would be appropriate.

 

2. If you want to perform an accurate analysis within the frequency range in which the frequency sweep will be performed, we recommend using Broadband rather than Single. Set Low Frequency to 1 MHz (the lowest frequency of the frequency sweep) and High Frequency to 200 MHz (the highest frequency of the frequency sweep).

 

3. Set the Solution Frequency to Broadband as mentioned above and manual mesh the transmission line.