The measurement of the complex impedance response accompanied by power absorption P(x) in
the radiofrequency and microwave ranges represents a most popular experimental method for the
investigation of pinning mechanisms and vortex dynamics in type-II superconductors. In the
theory, the pinning potential (PP) well for a vortex must be a priori specified in order to subsequently
analyze the measured data. We have theoretically solved the inverse problem at T¼0K
and exemplify how the coordinate dependence of a PP can be determined from a set of experimental
curves P(xjj0) measured at subcritical dc currents 0<j0<jc under a small microwave
excitation j1 jc with frequency x. We furthermore elucidate how and why the depinning frequency
xp, which separates the non-dissipative (quasi-adiabatic) and the dissipative (high-frequency)
regimes of small vortex oscillations in the PP, is reduced with increasing j0. The results
can be directly applied to a wide range of conventional superconductors with a PP subjected to
superimposed dc and small microwave ac currents at T Tc