Magnetron unit with choke structure for reducing higher harmonics in microwave output

Claim 1

A magnetron comprising: an anode cylinder having a plurality of vanes extending radially from an inner surface thereof, said anode cylinder having first and second open ends; a cathode disposed within said anode cylinder and coaxial therewith; a cathode stem air-tightly coupled with said second open end of said anode cylinder, for supporting said cathode; and an output section for delivering microwave energy from said magnetron, said output section comprising: an insulative cylinder having a first open end air-tightly coupled with said first open end of said anode cylinder and a second open end; an electrically conductive annular member, coaxial with said insulative cylinder and air-tightly fitted to said open end of said insulative cylinder, said annular member having a step portion acting as a seat for a cap, said annular member further including a first width portion above said step portion and a second width portion below said step portion, said first width being larger than said second width; an electrically conductive metal cap coaxial with said annular member and air-tightly fitted therewith, said cap providing an air tight seal for said annular member, said electrically conductive metal cap being force fitted against a wall of said first width portion when it is seated on said step portion; an output conductor having a first end coupled to at least one vane for conducting microwave energy from said anode cylinder to said cap, the metal cap and output conductor defining at least a portion of a first choke structure for suppressing a second harmonic component of the microwave energy generated within said anode cylinder, and the annular member defining at least a portion of a second choke structure for suppressing a fourth hormonic component of the microwave energy generated within said anode cylinder.