Patent ID: 6844680

Claim:
A magnetron, in which both a strap-engaging concave portion for joining a strap ring and a strap-inserting concave portion for inserting therethrough the strap ring in a non-contact manner are provided on an upper edge and a lower edge of each of anode vanes in a manner that the strap-engaging concave portion and the strap-inserting concave portion are positionally shifted from each other along a radial direction of an anode tubular body; the anode vanes arranged along a circumferential direction are electrically connected to each other by any one of a small-diameter strap ring and a large-diameter strap ring coaxially arranged with respect to a center axis of the anode tubular body, is joined to the strap-engaging concave portion; and a microwave radiating antenna passing through an output-sided magnetic piece in a non-contact manner is joined to one anode vane among the anode vanes, wherein, in such a case that a radial dimension of an outer circumference of the small-diameter strap ring is Rs 1 a radial dimension of an inner circumference of the large-diameter strap ring is Rs 2 a radius of a circumference inscribed to tip portions of the anode vanes is Ra and a radius of a central flat portion of the output sided magnetic piece located in a vicinity of each of the anode vanes is Rp, values of Ra, Rs 1 , Rs 2 , Rp are set in a manner that satisfies both following formulae (1) and (2): 1.85 Ra ≦( Rs 1 + Rs 2 )/ 2≦l.96 Ra (1) Rs 1 < Rp<Rs 2 (2).