HIGH FREQUENCY MULTIMODE FEED, AND ANTENNA COMPRISING SUCH A FEED

摘要

A multimode ultrahigh-frequency source with wide passband comprises a rectangular waveguide with a cavity terminating at an exit aperture in a horizontally flared horn, an input end of the cavity remote from the horn being joined at a transverse discontinuity plane to an upper and a lower pair of symmetrically disposed rectangular supply guides that are vertically separated from each other. An obstruction in the form of a block located between the levels of the supply guides extends from the discontinuity plane forward into the cavity and converges toward the horn in the vertical E-plane, e.g. with a trapezoidal cross-section. With the supply guides excited in the basic TE10 mode, a suitable dimensioning of the block will maintain a cophasal relationship between this basic mode and a hybrid mode EM12, originating at the discontinuity plane, in the exit aperture of the cavity over a wide frequency band.