Patent ID: 8441193

Claim:
An electronic frequency tuning magnetron comprising: an anode for forming a resonant cavity which is segmented into a plurality of spaces in an inner periphery side of a cylindrical anode shell; a cathode provided at the center of the anode shell along its cylindrical axial direction; and an exhausted structure having a coaxial central conductor which is connected to the inside of the resonant cavity in the anode shell and is coupled to the resonant cavity in a high-frequency band; wherein the coaxial central conductor is externally led through a wall of the exhausted structure via a through-hole, and the through-hole is closed by a dielectric portion placed between the coaxial central conductor and the wall of the exhausted structure, so as to keep a low atmosphere of the resonant cavity; wherein a switching element is connected in series or parallel to an end or a side surface of an external conductor comprising a led portion of the coaxial central conductor or a conductor which is connected to the coaxial central conductor, the led portion being a portion led out from the exhausted structure, wherein a bias voltage is applied to a potential of the anode shell via the switching element, thereby an oscillating frequency is adjusted by varying a bias current caused by the bias voltage, and wherein the external conductor and the switching element are covered with the coaxial external conductor, and an end of the switching element is electrically led to an outside of the coaxial external conductor via a conductor without electrically touching to the coaxial external conductor.