# Asymmetric amplitude (asymmetry)

A difference in amplitude at symmetric locations on the same resonator where the amplitude would be expected to be equal. Slight amplitude asymmetry may be caused by machining tolerances or variations in material properties within the resonator. Significant asymmetry is usually caused by interaction between the specified resonance and a close asymmetric resonance.

For any set of symmetric locations, the asymmetry at those locations is defined as:

\begin{align} \label{eq:11401a} \textsf{Asymmetry (%)} &= \left[ \frac{\textsf{Highest amplitude - Lowest amplitude}}{\textsf{Highest amplitude}} \right] 100 \end{align}

where all amplitudes are measured in the same direction (e.g., generally axial).

If all amplitudes at the symmetric locations are equal (i.e., highest amplitude = lowest amplitude), which is generally the desired condition, then the asymmetry = 0%. The worst asymmetry occurs when the lowest amplitude = 0 for which the asymmetry = 100%.

Asymmetry may exist at several locations on the resonator (e.g., at the corners of the face, over the slot webs, etc.). The overall resonator asymmetry is the highest asymmetry of all of these asymmetries.

Also see —
Amplitude droop
Amplitude rise
Uniformity