Abstract: In a magnetron for microwave oven, a high-voltage input terminal structure 30 is provided on a shield box 26 mounted on a magnetron unit 22. The high-voltage input terminal structure 30 has a cylindrical earth electrode 33, a cylindrical high potential inner electrode 32 and a central conductor 31a. The cylindrical earth electrode 33 is secured to the shield box 26 and the cylindrical high potential inner electrode 32 is coaxially arranged in the cylindrical earth electrode 33. The central conductor 31a is connected through an inductor 28 to a cathode lead 27 of the magnetron unit 22. An insulating resin 34b is filled in a gap between the cylindrical earth electrode 33 and the highpotential electrode 32 to form a capacitor section C. Cylindrical insulating sheaths 37, 38 are formed by the resin on the both sides of the capacitor section C. The capacitor section C and the cylindrical insulating sheaths, 37, 38 are integrally formed and continuously extended along a straight line.

Abstract: Disclosed is a magnetron for a microwave oven which has a drain electrode (60) near a cathode (25) and in a position where an electron beam path is not interfered with. The cathode and the drain electrode are formed in spiral shapes. Turns of the cathode are alternately arranged with those of the drain electrode. When the magnetron is operated, the drain electrode is kept at the same potential as the cathode or is kept at a negative potential relative to that of the cathode. Therefore, positive ions in the vicinity of the cathode are collected at the drain electrode, thus decreasing high frequency noise.

Abstract: A magnetron is provided with an anode cylinder having a number of resonance cavities defined in the anode cylinder and a cathode disposed along the axis of the anode cylinder. The anode cylinder is hermetically sealed by cover plates. An antenna section electrically connected to the resonance cavities is mounted on one of the cover plates, and a cylindrical envelope of a cathode stem is mounted on the other cover plate. Within the cylindrical envelope are disposed a rod holder electrically connected to one end of the cathode and a cylindrical holder connected to the other end of the cathode, the rod holder extending through the cylindrical holder, and the cathode is supported by both the holders. Within the cylindrical envelope is further disposed a dielectric cylinder, through which the cylindrical holder extends.

Abstract: A magnetron for microwave ovens, wherein the thickness d of a coiled filament constituting a cathode in the axial direction of the cathode bears a ratio d/p of 0.3 or less to the pitch p of turns of the coiled filament in the axial direction of the cathode.

Abstract: The magnetron of this invention comprises permanent magnets, resonant cavity unit and microwave-oscillating member such as a filament all set in a cylindrical yoke made of soft magnetic material and used as an evacuated envelope. The magnetron is forced into an opening bored in a fitting board, or inserted into said opening, followed by tightening. This fitting board enables the magnetron to be easily mounted on a waveguide or microwave oven.

Abstract: A high frequency electromagnetic energy absorber disposed near a cathode holder in an evacuated envelope of a magnetron so as to attenuate high frequency noise leaking through the cathode terminal of the magnetron. The absorber is in thermal contact with a member connected to the anode cylinder of the tube to conduct heat generated in the tube, whereby overheating of the tube can be prevented. By combining the absorber with another high frequency attenuating element, the attenuating effect can be increased.

Abstract: In a magnetron of the permanent-magnet-externally disposed-type wherein a pair of permanent magnets are disposed outside an anode cylinder, a yoke magnetically coupling the pair of permanent magnets to each other is extended along the side wall of an anode cylinder of the magnetron, and this anode cylinder is securely fixed to the yoke. The permanent magnets are each supported between the yoke and a seal plate for sealing the opening of the anode cylinder of the magnetron.

Abstract: A magnetron for oscillating ultrashort waves by uniformly applying a magnetic field to electrons, which comprises a cylindrical electrode assembly consisting of concentrically arranged cathode and anode electrodes; a magnetizing device formed of a pair of mutually facing permanent magnets prepared from rare earth so as to apply a magnetic field at right angles to electrons emitted from the cathode electrode to the anode electrode; and wherein the mutually facing magnetic pole surfaces of the paired permanent magnets are so depressed as to present a surface shaped in the form of a revolving ellipsis in order to apply a uniform magnetic field to electrons for control of their orbit, thereby producing from an outlet circuit oscillated electric waves which have resonated in the resonance cavity section of the anode electrode.

Abstract: A magnetron which has a plurality of vanes defining resonant cavities in an anode cylinder and straps connecting equipotentially alternate vanes and is provided at both ends of the anode cylinder with a device for generating a magnetic field in an interaction space in an axial direction of the anode cylinder. The straps are made of magnetic material.

Abstract: A magnetron having a hollow cylindrical anode having resonance cavities formed therein and a cathode arranged in the axial direction of the anode, wherein one open end of the hollow cylindrical anode is fitted hermetically with a conductor plate electrically connected to the anode; a slot antenna is provided on the conductor plate; one end of an output conductor, the other end of which is connected to the resonance cavities, extends to the feeding point of the slot antenna for obtaining a microwave output.

Abstract: A magnetron includes a "horizontally blow" type radiator consisting of a plurality of cooling plates press fitted one over the other over the outer periphery of a cylindrical anode member to permit a cooling wind to be blown in a direction to intersect the axis of the anode member, and a cooling wind guide for guiding toward the radiator the cooling wind blown, in the direction of the axis of the anode member, from the side of a cathode stem extending from one side of the anode member.