Patent ID: 7906912

Claim:
A magnetron, comprising: a cylindrical-shaped anode barrel member having two openings respectively formed in the two end portions thereof; a cathode structure member disposed on the center axis of the anode barrel member; more than one anode vane disposed radially through an action space in the periphery of the cathode structure member and fixedly mounted on the inner wall surface of the anode barrel member; and a funnel-shaped input side pole piece disposed on the side of one of the two openings of the anode barrel member for supply of power to the cathode structure member, the input side pole piece including a small-diameter flat portion having a penetration hole formed in the central portion thereof, a large-diameter flat portion having a diameter larger than the diameter of the small-diameter flat portion, and a conical-shaped slanting portion for connecting the large-diameter flat portion and small-diameter flat portion to each other, wherein the input side pole piece further includes, besides the penetration hole formed in the central portion of the small-diameter flat portion, three or more penetration holes respectively formed in the slanting portion thereof.