Multimode horn antenna

Claim 2

A horn antenna comprising: a funnel-shaped coupling member having two orthogonal symmetry planes and having an aperture at the narrow end adapted to excite a symmetrical mode wave therein and a larger diameter aperture at the opposite end, a first pair of side wall coupling apertures in the side wall of said member at diametrically opposite surfaces of the member in one symmetry plane, a second pair of side wall coupling apertures in the side wall of said member at diametrically opposite surfaces of said member in the second of said orthogonal symmetry planes, said first and second pair of side wall coUpling apertures being adapted to excite two orthogonal asymmetrical modes, a waveguide section of a diameter large enough to support said symmetrical mode and small enough to reflect said asymmetrical modes and smaller than the diameter of the aperture at the narrow end of said member coupled by a first step to said narrow end of said member, a cylindrical waveguide of a diameter larger than said larger diameter aperture of said member coupled by a second step to said opposite end of said member, said cylindrical waveguide section having a ring-like member dividing said cylindrical waveguide into two sections, said first and second steps and said ring-like member being dimensioned and arranged so that the two main lobes in the radiation patterns associated with the two asymmetrical modes have substantially the same beamwidth pattern of the single main lobe radiation pattern associated with the symmetrical mode.

Claim 3

The combination in claim 1 including a choke in the outer surface wall of said cylindrical waveguide.

Claim 4

A variable beam position antenna comprising, in combination: a hollow member having a first opening at one end and an opening at the opposite end; a plurality of side wall coupling apertures in the side wall of said member; a first power divider means coupled between said plurality of side wall coupling apertures and a terminal thereof for in response to signal waves coupled to said terminal power dividing said waves and coupling the power divided waves in a given phase relationship to said side wall apertures to excite within said member a first asymmetrical difference mode that provides a radiated pattern with two main out of phase lobes; means adapted at said one end of the hollow member to couple a symmetrical mode wave and reflect said asymmetrical difference mode waves, and means at said opposite end to couple said symmetrical and asymmetrical modes, and a controllable power divider means adapted to be coupled to a source of signal waves for coupling signal waves of a selected percentage of the power from said source to said one end, whereby a symmetrical mode radiated pattern with one main lobe is produced, and for coupling signal waves at the remaining power from said source to said terminal of said first power divider means.

Claim 5

A variable beam position antenna comprising, in combination: a hollow member having a first opening at one end and an opening at the opposite end; a plurality of side wall coupling apertures in the side wall of said member; a first power divider means coupled between said plurality of side wall coupling apertures and a terminal thereof for in response to signal waves coupled to said terminal power dividing said waves and coupling the power divided waves in a given phase relationship to said side wall apertures to excite within said member a first asymmetrical difference mode that provides a radiated pattern with two main out of phase lobes; means adapted at said one end of the hollow member to couple a symmetrical mode wave and reflect said asymmetrical difference mode waves, and means at said opposite end to couple said symmetrical and asymmetrical modes, and a controllable power divider means adapted to be coupled to a source of signal waves for coupling signal waves of a selected percentage of the power from said source to said one end, whereby a symmetrical mode radiated pattern with one main lobe is produced, and for coupling signal waves at the remaining power from said source to said terminal of said first power divider means.

Claim 6

The combination claimed in claim 3, wherein said member is a funnel-shaped member.

Claim 7

The combination claimed in claim 3, wherein said member has two orthogonal symmetry planes.

Claim 8

The combination claimed in claim 5, wherein a first pair of said plurality of side wall apertures is in a first of said planes and a second pair of said plurality of side wall apertures is in a second of said planes orthogonal to said first plane.

Claim 9

The combination claimed in claim 6, including means coupled to said one end for controlling said symmetrical mode and means coupled to said opposite end for controlling said asymmetrical mode whereby the two out of phase difference lobes in the pattern associated within the asymmetrical mode fall within the main pattern lobe associated with the symmetrical mode.

Claim 10

The combination claimed in claim 6 wherein said two asymmetrical difference modes are the TE12 mode and a hybrid TM01 + TE21 mode.

Claim 11

The combination claimed in claim 6 wherein said first power divider means includes a second terminal which in response to signal waves coupled thereto power divides said waves and couples these power divided waves in a phase relationship to excite within said member a second asymmetrical difference mode orthogonal to said first asymmetrical difference mode.

Claim 12

A variable beam position antenna comprising, in combination: a funnel-shaped hollow member having two orthogonal symmetry planes and a first opening at one end and a larger opening at the opposite end adapted to be coupled to free space; a first terminal means coupled to said one end; first and second apertures in the side waLl of said member at diametrically opposite surfaces of the member in one of said symmetry planes; third and fourth apertures in the side wall of said member at diametrically opposite surfaces of said member in the second of said planes; second and third terminal means; means coupled between the first, second, third and fourth apertures and said second and third terminal means for, in response to signal waves at said second terminal means, equally distributing the energy of said signal waves applied thereto to each of said side wall apertures with signal waves at the first and third side wall apertures being advanced 90* relative to signal waves at the remaining second and fourth side wall apertures and for, in response to signal waves at said third terminal means, equally distributing the energy of said signal waves applied thereto to each of said sidewall apertures with the signal waves at the second and fourth apertures being advanced 90* relative to the signal waves at the first and third sidewall apertures; a controllable power divider means adapted to be coupled to a source of radio frequency signals for power dividing said signals in a selective manner to provide at least one half of the signal energy of said signals at said source to said first terminal means, whereby a symmetrical mode pattern is exited in the member, and the remaining percentage of signal energy of said signals at said source to a selected one of said second and third terminals in either a selective in phase at 180* out of phase relationship with said signals applied to said first terminal.

Claim 13

A variable beam position antenna comprising, in combination: a funnel-shaped hollow member having two orthogonal symmetry planes and a first opening at one end and a larger opening at the opposite end adapted to be coupled to free space; a first terminal means coupled to said one end; first and second apertures in the side waLl of said member at diametrically opposite surfaces of the member in one of said symmetry planes; third and fourth apertures in the side wall of said member at diametrically opposite surfaces of said member in the second of said planes; second and third terminal means; means coupled between the first, second, third and fourth apertures and said second and third terminal means for, in response to signal waves at said second terminal means, equally distributing the energy of said signal waves applied thereto to each of said side wall apertures with signal waves at the first and third side wall apertures being advanced 90* relative to signal waves at the remaining second and fourth side wall apertures and for, in response to signal waves at said third terminal means, equally distributing the energy of said signal waves applied thereto to each of said sidewall apertures with the signal waves at the second and fourth apertures being advanced 90* relative to the signal waves at the first and third sidewall apertures; a controllable power divider means adapted to be coupled to a source of radio frequency signals for power dividing said signals in a selective manner to provide at least one half of the signal energy of said signals at said source to said first terminal means, whereby a symmetrical mode pattern is exited in the member, and the remaining percentage of signal energy of said signals at said source to a selected one of said second and third terminals in either a selective in phase at 180* out of phase relationship with said signals applied to said first terminal.