The impedance for a non-piezoelectric element (of the same shape and dielectrical properties) is
also shown in blue.
The presence of electrical resonances and anti-resonances make the piezoelectric impedance unique.
The resonances result from the electrical input signal exciting
a mechanical resonance in the piezo element.
For each mechanical resonance in the piezo element, a resonance/anti-resonance pair
will exist in the impedance.
This characteristic piezoelectric impedance can be modeled by an equivalent circuit.