Microwave magnetron-type device

A magnetron comprising, an anode block comprising a multistage two-dimensional periodic retarding system and having a cylindrical central chamber, a cathode in said central chamber coaxial therewith, said anode block having a plurality of paired solid vanes disposed laterally spaced in a circumferential direction and extending inwardly of said chamber toward said cathode with the pairs thereof defining a plurality of resonator cavities, each vane having a root end and a free end terminating at said central chamber spaced outwardly from said cathode and having substantially flat sidewalls defining said resonator cavities, each cavity diverging from the free ends of the paired vanes toward the root ends thereof, each of said resonator cavities having a distributed inductance portion adjacent said root ends, said vanes having through windows on each stage of said retarding system, each of said through windows having a sidewall closer to the root end of a corresponding vane and an opposite sidewall closer to the free end of the corresponding vane, coaxial paired straps extending through the windows transversely of the vanes and each connected to a different group of alternate vanes, each of said vanes having an opening aligned with an opening of the adjacent vane to define a duct extending through all of the vanes in the vicinity of the distributed inductance portions thereof, and the magnetron having a frequency range including the long-wave range of the microwave frequency range greater than if the vanes did not have the aligned openings.