| 摘要 |
A waveguide feed structure having a coaxial transmission line. A conductive, planar septum is disposed in, and along a diameter of, the transmission line. A feed port is electrically coupled to the transmission line. The septum has a rear portion disposed proximate the feed port, such rear portion of the septum extending between the inner conductor and the outer conductor. The feed port and the rear portion of the septum are arranged to establish an electric field in the transmission line between the inner conductor and the outer conductor with a component substantially TE11 mode along a direction perpendicular to the planar septum. A forward portion of the septum is asymmetrically disposed with respect to said diameter in order to provide a gap between the inner conductor and the outer conductor, such gap establishing an electric field component within the transmission line having a TE11 component along said diameter of the transmission line parallel to the plane of the septum. The septum has a pair of distal ends. One of the ends is separated from a proximate portion of the outer conductor and has a distance different from the separation between the other one of the pair of ends and a proximate portion of the outer conductor. In one embodiment, the first-mentioned distance increases along the transmission line from the rear portion of the septum to the forward portion of the septum. The distance is increased in steps to provide a 90 degree phase shift to energy propagating along the transmission line between a distal end of the septum and the outer conductor.
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