Patent ID: 7148627

Claim:
A magnetron comprising: a cylindrical anode cylinder being open at one of the ends thereof, a metal cylinder hermetically sealed at the opening end of said anode cylinder via a magnetic pole piece, a third harmonic restraint cylindrical choke and a fifth harmonic restraint cylindrical choke disposed coaxially inside said metal cylinder, a plurality of anode segments disposed on the inner face of said anode cylinder so as to be directed toward the central axis thereof, an antenna lead connected to a desired position of said anode segment, an output portion connected to said antenna lead passing through said magnetic pole piece and said metal cylinder so as not to make contact therewith and insulated from said metal cylinder, wherein said metal cylinder and said third harmonic restraint cylindrical choke disposed therein constitute a quarter-wave choke for a third harmonic frequency band, and said third harmonic restraint cylindrical choke and a fifth harmonic restraint cylindrical choke disposed therein constitute a quarter-wave choke for a fifth harmonic frequency band, and the electrical length (L 1 ) of said antenna lead from the connection end of said anode segment to the opening end of said third harmonic restraint cylindrical choke is 1/2 of the wavelength of the third harmonic.