Magnetron having coaxial choke means extending into the output side insulating tube space

A magnetron for producing microwave energy at a predetermined fundamental frequency comprising:

• an anode of cylindrical shape;
• a plurality of vanes attached to said anode;
• a cathode disposed inside of and spaced from said anode for emitting electrons;
• a cylindrical metallic container for realizing an airtight inner space integral with and extending from one end of said anode;
• an output-side insulating tube having one end thereof airtightly connected to said cylindrical metallic container at a point spaced from said anode and having the other end thereof extending outwardly of said container;
• an antenna conductor electrically coupled with one of said plurality of vanes and extending through the inner space of said cylindrical metallic container and through said output-side insulating tube;
• and
• coaxial choke means for suppressing a higher harmonic of said fundamental frequency comprising a choke portion of a length (d) having one end thereof connected to said cylindrical metallic container and having the other end thereof extending into the output-side insulating tube and said choke means surrounding the antenna conductor;
• the length (d) of said extending choke portion of said cylindrical metallic body being longer than a distance between said other end of said output-side insulating tube and said other end of said choke portion.