Learning Forum

[hyhaerong]

Hello,

I’m working on matching a loop antenna structure in HFSS for 13.56 MHz wireless power transfer. As shown in the attached screenshots, I set up a coil geometry with a lumped port and added lumped RLC components to implement the matching network (marked in the model).

I am trying to sweep L and C values to match the impedance at 13.56 MHz. The setup is similar to how we do Smith chart matching in circuit simulators — I applied the lumped elements directly onto the structure boundaries and swept the values (Cap: 500 pF to 5000 pF, step 500 pF; Ind: 100 nH fixed for now).

However, no matter what I do, the impedance always stays near the edge of the Smith chart, never getting close to the center. I also tried different combinations of L and C, in both series and parallel configurations, or just using C alone for both parts, but nothing brings the reflection coefficient down. Interestingly, some weak resonances appear around 17 MHz, but not at 13.56 MHz.

Could this be a problem with the way I'm modeling the lumped components in HFSS? Or perhaps something about the coil geometry or port definition?

Any advice would be greatly appreciated.

Thanks in advance!

 

[Praneeth]

Hi,

Thank you for reaching out to the Ansys Learning forum.

Please go through my comments and suggestions:

1. Have you verified if your design is correctly simulated? Like, have you verifed S21 of your model in the absence of lumped elements in both the coils?
2. You can do co-simulation of your HFSS design with AEDT Circuit to get the L and C values required for the matching circuit and their interconnection.
3. It looks like you have two lumped RLC boundaries defined?

Kindly check and respond back.

Best regards,
Praneeth,

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