Shortened dual-mode horn antenna

Claim 1

A horn antenna arrangement, comprising: a hollow waveguide including a conductive peripheral wall arrangement centered on a longitudinal axis; a conductive short circuiting plate connected to said peripheral wall arrangement at a first plane transverse to said axis; an elongated conductor connected at one end to said short circuiting plate and extending within said waveguide and centered on said axis to an abrupt termination at a second plane transverse to said axis, said elongated conductor being electrically isolated from said conductive peripheral wall arrangement at transverse planes other than said first plane; push-pull feed means coupled to said hollow waveguide at a third transverse plane lying between said first and second transverse planes, for transducing a signal with said waveguide with first and second antiphase electric poles at diametrically opposite sides of said axis; and a radiation aperture centered on said axis and defined at an extension of said hollow waveguide said radiation aperture being separated by a predetermined distance from said second plane which is selected to provide a phase difference of 180° between a fundamental waveguide mode and a higher-order waveguide mode at said radiating aperture for tending to equalize the radiation patterns in two orthogonal planes.

Claim 7

A method for generating a radiated field, comprising the steps of: generating a coaxial field propagating mode in a hollow conductive structure coaxial with and electrically isolated from a center conductor; converting a portion of said coaxial field propagating mode to a higher-order waveguide field propagating mode at a particular transverse plane of said hollow conductive structure having a center conductor; propagating said fundamental waveguide mode and said higher-order mode for a length corresponding to a differential phase of 180° plus the product of N multiplied by 360°, where N is an integer, to form a net field distribution which is tapered in amplitude; and generating a radiated field having characteristics determined by said net field distribution.

Claim 8

A method for generating a radiated field, comprising the steps of: generating a coaxial field propagating mode in a hollow conductive structure coaxial with and electrically isolated from a center conductor; converting a portion of said coaxial field propagating mode to a higher-order waveguide field propagating mode at a particular transverse plane of said hollow conductive structure having a center conductor; propagating said fundamental waveguide mode and said higher-order mode for a length corresponding to a differential phase of 180° plus the product of N multiplied by 360°, where N is an integer, to form a net field distribution which is tapered in amplitude; and generating a radiated field having characteristics determined by said net field distribution.