A method, comprising: providing, by a radio frequency signal source through a transmission path, an RF signal to an electrode that is proximate to a cavity of a defrosting system; establishing an initial configuration of a variable impedance matching circuit configured to perform an impedance transformation from an impedance of the RF signal source to an input impedance of the cavity plus a load in the cavity; repeatedly determining a forward RF power measurement and a reflected RF power measurement along the transmission path and calculating the ratio of the reflected RF power measurement to the forward RF power measurement; determining, that the rate of change of the ratio has transitioned from a relatively high value to a relatively low value; and at a point in time when the determination is made that the ratio has transitioned to the relatively low value: determining, based upon a historical rate of change of the forward RF power measurement and the reflected RF power measurement, an additional time duration for provision of the RF signal to the electrode to achieve a desired state of the load in the cavity of the defrosting system, continuing to provide the RF signal to the electrode for an additional time duration beyond the point in time when the determination is made that the ratio has transitioned to the relatively low value, and ceasing provision of the RF signal to the electrode when the additional time duration has expired. providing, by a radio frequency signal source through a transmission path, an RF signal to an electrode that is proximate to a cavity of a defrosting system; establishing an initial configuration of a variable impedance matching circuit configured to perform an impedance transformation from an impedance of the RF signal source to an input impedance of the cavity plus a load in the cavity; repeatedly determining a forward RF power measurement and a reflected RF power measurement along the transmission path and calculating the ratio of the reflected RF power measurement to the forward RF power measurement; determining, that the rate of change of the ratio has transitioned from a relatively high value to a relatively low value; and at a point in time when the determination is made that the ratio has transitioned to the relatively low value: determining, based upon a historical rate of change of the forward RF power measurement and the reflected RF power measurement, an additional time duration for provision of the RF signal to the electrode to achieve a desired state of the load in the cavity of the defrosting system, continuing to provide the RF signal to the electrode for an additional time duration beyond the point in time when the determination is made that the ratio has transitioned to the relatively low value, and ceasing provision of the RF signal to the electrode when the additional time duration has expired. determining, based upon a historical rate of change of the forward RF power measurement and the reflected RF power measurement, an additional time duration for provision of the RF signal to the electrode to achieve a desired state of the load in the cavity of the defrosting system, continuing to provide the RF signal to the electrode for an additional time duration beyond the point in time when the determination is made that the ratio has transitioned to the relatively low value, and ceasing provision of the RF signal to the electrode when the additional time duration has expired.