GB634640A - Improvements in or relating to magnetrons - Google Patents

Abstract

634,640. Magnetrons. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. March 19, 1946, No. 8545. Convention date, March 22, 1945. [Class 39 (i)] A magnetron has an anode assembly comprising a plurality of adjacent and contacting approximately U-shaped elements 18 nested in a casing 10, the open ends of the elements surrounding a central space containing the cathode 13, and their legs converging radially towards the central space with their ends constituting anode segments. A conducting ring 19 is silver-soldered to alternate pairs of contacting legs and a second conducting ring 20 is silver-soldered to the pairs of legs between the said alternate pairs of legs to help # mode of oscillation. Straps respectively connecting alternate and intermediate pairs of legs could replace the rings 19 and 20. Tuning means comprise a coaxial line cavity resonator having an inner conductor 26 electrically connected at 26<1> to the conducting ring 19 and an outer conductor 25 lying along and electrically connected to a pair of legs connected to the other conducting ring 20. The outer conductor 25 is connected to the tubular member 27 provided with a threaded member 28 connected to the outer conductor 35 of a coaxial line cavity resonator having an inner conductor 40 connected to the conductor 26 and a slidable tuning ring 41. If both conducting rings 19 and 20 are mounted at one end of the magnetron as in Fig..4 they could both be directly connected to the coaxial line. The conductor 26 is shielded by the conductor 25 and this shielding is improved in the construction shown in Fig. 3 by the conductor 30 provided with a shield extension 31. The tuning arrangement 25, 26 is located with respect to the load loop 22 so that the desired mode of oscillation, usually the # mode, is obtained without distortion of the field intensities. This mode is favoured by having the tuning arrangement 25, 26 situated at some angle other than 90, 180 or 270 degrees from load line 22, 23. The leads 14 and 15 to the indirectly heated cathode 13 extend through the casing 10 which may be of stainless steel or of metal known under the Registered Trade Mark " Monel " or other non-magnetic material and are located in a plane bisecting a cavity resonator so that only a negligible amount of high-frequency power passes out through these leads. A corrugated radiator element 21 is secured to the exterior of the casing 10 for cooling purposes and a cooling medium can be directed between the casing and the open corrugations.