Abstract: A magnetron has a cathode, an anode with vanes, and an insulating surface which faces the cathode and receives material from the cathode due to sputtering at the cathode. A conductor enables the resistance of the film so deposited to be measured, giving an indication of the thickness of the film and the lifetime of the magnetron.

Abstract: A magnetron having a cathode 1 and an anode 2 with vanes 3, has an insulating surface 4 in it which faces the cathode and receives material from it due to sputtering at the cathode. A conductor 7 enables the resistance of the film so deposited to be measured, giving an indication of the thickness of the film and the lifetime of the magnetron.

Abstract: In a magnetron having a body 1 defining an anode 2 divided into resonant cavities 4 by vanes 3 and having a coaxial cathode 5, r.f. energy produced when a magnetic field is applied parallel to the axis of the anode is launched along a waveguide 8 by an antenna 6 in an evacuated region of the magnetron closed by a dielectric window 19. The latter has sector shaped conducting areas on its surface symmetrically arranged with respect to the antenna, the inductance of which balance the capacitance of the dielectric window, thereby reducing reflections at the window.

Abstract: A magnetron includes an anode having at least one vane defining a plurality of cavities and a dielectric resonator in communication with the at least one vane. The dielectric resonator is arranged to at least partially absorb radiation generated in a predetermined mode of operation of the magnetron.

Abstract: A magnetron output arrangement includes a coaxial output adapted to be coupled in an endfire configuration to a rectangular waveguide. The waveguide has a flange for mating with the magnetron output arrangement. The coaxial output includes a central conductor. The output arrangement further includes a plate located in a predetermined position with respect to the central conductor. The plane of the plate is arranged to be substantially perpendicular to the axis of the coaxial output. The plate is located a predetermined distance from the end of the central conductor, such that the coaxial output in use couples with the plate so that the output coupling is substantially the same regardless of the type of waveguide flange employed.

Abstract: A magnetron has an output comprising a coaxial line 15 which transmits energy from a wanted oscillator mode as a first coaxial waveguide mode and energy from an unwanted oscillator mode as a second cylindrical waveguide mode. Energy in the cylindrical waveguide mode is intercepted by slots 17, 18 in the coaxial line 15 and absorbed by material 10. This enables the modes to be separated. Preferably, the output is taken from the axis of the magnetron and the wanted oscillator mode is the &pgr; mode.

Abstract: A magnetron comprises an anode (2) having vaner (3a, 3b) which define a plurality of cavities. A dielectric resonator (7) is located such that it is in communication with at least one of the vanes (3a, 3b). In use, the dielectric resonator (7) at least partially absorbs spurious radiation generated in a predetermined mode of operation of the magnetron, such as the &pgr;-1 mode. Power generated in the &pgr;-1 mode, if transmitted, may interfere with other electronic devices. The resonator (7) may be of ceramics material, such as alumina.

Abstract: An anode structure for a magnetron includes T-shape anode vanes having a radially extensive component and a circumferentially extensive portion, the cylindrical faces of the circumferential portion facing a cathode in the complete magnetron. The use of T-shape vanes increases inductance and hence permits low frequency radiation to be generated without increasing the dimensions of the magnetron compared to those of a conventional magnetron. Also, capacitance is increased to give a further reduction in frequency by using more than two anode straps, and preferably four anode straps at each end of the anode structure. Preferably, the anode structure is incorporated in a magnetron in which a high magnetic field of the order of 500 Gauss for a magnetron operating at 100 MHZ is used. The anode shell itself may form part of the magnetic return path. Other anode vane configuration, for example L-shaped, may be used.

Abstract: A magnetron has an output comprising a coaxial line 15 which transmits energy from a wanted oscillator mode as a first coaxial waveguide mode and energy from an unwanted oscillator mode as a second cylindrical waveguide mode. Energy in the cylindrical waveguide mode is intercepted by slots 17, 18 in the coaxial line 15 and absorbed by material 19. This enables the modes to be separated. Preferably, the output is taken from the axis of the magnetron and the wanted oscillator mode in the &pgr;-1 mode.

Abstract: The invention relates to a resonant cavity device such as a magnetron oscillator which is tunable by means of a tuning plunger associated with sealing bellows. A volume defined at least in part by the bellows and producing a range of spurious responses as the tuning plunger is moved is isolated from the resonant cavity or cavities of the device by an isolating choke. The choke may take the form of an annulus having a major radius of 1/4 .lambda. (where .lambda. is the mid-frequency of the tuning range) attached either to the plunger or to the main body of the device and between the bellows and the resonant cavity or cavities.

Abstract: This invention relates to a co-axial magnetron in which a separate resonator incorporating a multipactor discharge arrangement is used to tune the operating frequency of the magnetron. The separate resonator is symmetrically coupled via couplers into the main resonator cavity of the magnetron. More than one separate resonant can be provided, in which case they are symmetrically coupled into the main resonant cavity to achieve correct tuning.