Abstract: The device according to the invention for generating hyperfrequency waves, of the magnetron type, comprises: a cathode, elongated between first and second longitudinal ends; an anode, surrounding the cathode and comprising an inner surface oriented toward the cathode and delimiting a plurality of resonant cavities distributed along the periphery thereof; and a voltage source, to establish a potential difference between the cathode and the anode. The cathode is electrically connected to the voltage source by each of its longitudinal ends, to bring those two ends to substantially equal electric potentials. The generating device also comprises a device for adjusting the longitudinal length of each resonant cavity, the adjusting device comprising at least one mobile element defining a longitudinal end of at least one resonant cavity.