# Discussion Forum

## Impedance Calculation in Surface Acoustic Wave Simulation

Hello,

I am using a simulation for Surface Acoustic Waves in the frequency domain in order to obtain impedance. Initially, I am employing two boundary probes, one to measure electric potential and the other to measure the norm of surface current density multiplied by the out-of-plane thickness. Then, in the results section for the 1D plot group, it was chosen to use the point graph where I calculate the impedance ratio (V/A) through both probes. The issue is that I am not obtaining satisfactory results. Am I approaching this incorrectly?

In the physics I am applying, a terminal is used as a source of AC voltage. I have a question regarding this. In the time domain study, I made a global definition (analytical) as a cosine wave dependent on time, but in the frequency domain study, this is not possible. Therefore, I decided to define a waveform (global definition), but I am uncertain if it is correct for obtaining impedance. What should I do instead of using this waveform?

Could someone help me with this problem?

Thank you, Regards, TM

3 Replies Last Post Feb 29, 2024, 3:27 p.m. EST

Posted: 6 months ago

In frequency domain impedance is a complex quantity.

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com

Posted: 5 months ago
Updated: 5 months ago

In frequency domain impedance is a complex quantity.

Hello,

I appreciate your reply, but I'm unsure about the changes I should make. I've found a section in the solving where I can select to split complex variables into real and imaginary parts. Is this the change you are referring to? Can you help me?

Thank you.

Posted: 5 months ago

It was meant as a hint that impedance is quantified in different ways in time and frequency domain. Your approach and your intentions are not really clear. So it is difficult to tell what to change. In frequency domain it is not required to define any waveform. The load is always a harmonic waveform with the frequency you set in the study step and the amplitude you set in the load node, e.g. the terminal voltage.

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com