Abstract: An rf load is matched to an rf source by a matching network having series and shunt impedances connected between the source and load. A network coupled to the load derives a first rf signal responsive to rf energy reflected from the load. Another network responsive to the first rf signal derives plural rf signals, each having an amplitude that is a different function of the magnitude and phase angle of the reflected energy. In response to the amplitudes of the plural rf signals, the values of the series and shunt impedances are controlled.

Abstract: A high Q load circuit is automatically matched to a drive circuit with an L network having a series reactance and a shunt reactance, one of which is on a load circuit side of the network and the other of which is on a drive circuit side of the network. The reactance on the load circuit side is of a type opposite to the reactance of the load, while the drive circuit reactance provides an approximate match between the drive and load circuits. Both reactances are varied until the voltage or current magnitude applied by the drive circuit to the network is at least equal to the voltage or current magnitude of the reactance on the input side. Then the reactances are varied until the voltage or current magnitude of the reactance on the input side is slightly less, by a predetermined amount, than the voltage or current of the reactance on the output side. For each unit change of the reactive value of the reactance on the load side, there is a small change in the reactive value of the reactance on the drive side.