Patent ID: 7212087

Claim:
A twisted waveguide comprising: first and second rectangular propagation path elements having different planes of polarization; and a connection element connecting the first and second rectangular propagation path elements, wherein the connection element has a fixed line length in a direction of electromagnetic-wave propagation of the first and second rectangular propagation path elements, and wherein the connection element includes projections which project inward so as to face each other, the projections concentrating an electric field of an electromagnetic wave entering from the first or second rectangular propagation path element and rotating a plane of polarization of the electromagnetic wave propagating through the connection element, and wherein an inner periphery of the connection element surrounding a central axis extending in the direction of electromagnetic-wave propagation of the first and second rectangular propagation path elements includes surfaces substantially parallel to an H plane and an E plane of the first rectangular propagation path element, said surfaces forming a staircase such that abutting sections between the surfaces parallel to the H plane and the surfaces parallel to the B plane form the projections, the staircase being inclined in a direction corresponding to a direction in which an H plane of the second rectangular propagation path element is inclined.