# Impedance of Z(1,1) is not 50 ohm in HFSS

1. ## Impedance of Z(1,1) is not 50 ohm in HFSS

Hi, i have designed the 3D spiral coil using HFSS and terminated it with 50 ohm impedance using single Lumped port. But the data table of Z(1,1) shows resistance value in terms of milliohms. What changes should be made to get correct values of resistance and inductance? How to obtain proper S11 at 10MHZ?

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2. ## Re: Impedance of Z(1,1) is not 50 ohm in HFSS

Looking at your screenshot, I suspect that you have a metal object in parallel to your lumped port.

I'm not an HFSS user, but in all my EM tools a lumped port is between the metals, and looks like a port (not like a metal).

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3. ## Re: Impedance of Z(1,1) is not 50 ohm in HFSS

make sure you converge for very low deltas. better even look at the variation of z11 rather than S. something like delta s of 0.002 may be better for inductor. if results are far off, something is wrong with geometry..

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4. ## Re: Impedance of Z(1,1) is not 50 ohm in HFSS

Originally Posted by dpres
make sure you converge for very low deltas. better even look at the variation of z11 rather than S. something like delta s of 0.002 may be better for inductor. if results are far off, something is wrong with geometry..
Hi.. thanks for your prompt response.

Hi Volker.. thanks for your valuable suggestion. I have defined the port between terminals using rectangular sheet. The data table shows some non-zero values. Let me check with that values.

5. ## Re: Impedance of Z(1,1) is not 50 ohm in HFSS

Looks much better, and imag{Z} scales with frequency as expected. I think you've solved your issue now.

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6. ## Re: Impedance of Z(1,1) is not 50 ohm in HFSS

Originally Posted by volker@muehlhaus
Looks much better, and imag{Z} scales with frequency as expected. I think you've solved your issue now.
Issue fixed. Inductance value is around 637nH. Thank you.

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