A low-power magnetron for microwave heating

A primary design consideration for a commercial microwave heating unit is low cost for the oscillator tube, the power supply, and the associated control circuits. This paper describes a magnetron design which makes possible price reduction in all these areas. In order to achieve a magnetron with these characteristics, it was necessary to depart, to some degree, from the conventional magnetron geometry. These deparures from convention which will be described were of a mechanical and an electrical nature. They include: a new type of "dipole type output system whereby the anode radiates directly into the load waveguide, use of the high-voltage bushings as output windows, and an all-welded assembly which permits unitized tube assembly and removal of all packaging parts from the tube, incorporating them in the tube socket. In addition, this output sysem resulted in this magnetron having a high mode boundary which made possible operation from an unrectified, unfiltered, power supply. With all these characteristics designed into the tube, it will be pointed out how this magnetron was capable of passing rigid test specifications. The magnetron described was developed for operation in the S-band microwave heating band. It is possible to modify this magnetron in such a manner that it can work in the L-band microwave heating band without changing its operating characteristics or dimensions.