Patent ID: 7667370

Claim:
A generating device ( 1 ) for generating a useful stream of a medium ( 2 ) comprising: at least a medium stream source ( 14 ) for generating at least a medium stream ( 15 ) in mutually opposed flow directions ( 16 ), modulating a first signal laying within a first frequency range to generate a second signal laying within a second frequency range, and alternating the mutually opposed flow directions ( 16 ) of the medium stream with the second signal lying within the second frequency range, said second frequency range covering frequencies that lie above those of the first frequency range; at least a medium stream diode ( 22 ; 25 ; 36 , 37 ) provided, constructed and arranged for cooperating with a stream of a medium generated by the at least one medium stream source working counter to said stream of the medium with flow resistances, and generating a total medium stream flowing in a transmission direction of the at least one medium stream diode; and at least one medium stream sink ( 23 , 24 ; 40 , 41 ) provided, constructed, and arranged for cooperating with the total medium stream generated by the at least one medium stream diode, suppressing stream components within the second frequency range contained in the total medium stream, and generating the useful stream of the medium ( 2 ) in the first frequency range without the stream components within the second frequency range at an output of the at least one medium stream sink ( 23 ; 40 ).