filtering is thus superfluous in most cases usually as much power as possible will be outfed this meaning that the interdigital transducer idw2 is dimensioned such that only the power required for maintaining the oscillation is present at the input of the amplifier 8 the majority of the power given a corresponding dimensioning can then be outfed from the oscillator circuit via the interdigital transducer idw3 another advantage of the sw resonator of the invention is that reactances of following circuits back to the oscillator circuit are minimized due to this type of signal outfeed when as shown in fig7 the interdigital transducer idw3 is terminated by a terminating impedance 10 having variable impedance then the oscillator frequency of the oscillator can be correspondingly controlled on the basis of this wiring since the interdigital transducer idw3 is thus eliminated as an element for outfeed of the oscillator signal the signal outfeed occurs via the circuit part 4 or via an additional interdigital transducer that is not shown in the drawing the sw resonator of fig3 can also serve as a power divider or as an addition element for signals see fig8 in the former instance for example the transducer idw1 is conceived as.