Antenna array system for generating shaped beams for guidance during aircraft landing

Claim 2

An antenna array for generating a shaped pattern for aircraft guidance during landing comprising an elongate hollow waveguide, a matched impedance load at one end of said waveguide, a wall of said waveguide having slots of substantially uniform size and shape formed therethrough and distributed along the length of said waveguide, the spacing of said slots along the length of said waveguide being arranged symmetrically about the midlength thereof and comprising a plurality of unequal spaces of selective size so that the phase of the electric field radiated from said slots will match a predetermined phase distribution curve along said waveguide, said predetermined phase distribution curve having a linear relative steep middle portion and relatively flat end portions and being symmetrical about a midpoint thereof, and coupling means disposed inside saiD waveguide, said coupling means including a plurality of coupling portions respectively disposed adjacent selected ones of said slots, said coupling portions being arranged symmetrically about the midlength thereof so that the amplitude of the electric field radiated from said slots matches a predetermined amplitude distribution curve which is peaked in its center and which is symmetrical about a line passing through said center.

Claim 3

An antenna array as recited in claim 1 wherein there is provided means to polarize the electric field radiated by each of said slots in the same direction.

Claim 4

An antenna array as recited in claim 2 wherein said means to polarize the field radiated from each of said slots comprises an open ended rectangular waveguide element for each slot positioned to receive in one end the energy passing through such slot and to radiate the energy from its opposite open end.

Claim 5

An antenna array as recited in claim 3 wherein means are provided to reduce the mutual coupling between the open ends of said waveguide elements.

Claim 6

An antenna array as recited in claim 4 wherein said means to reduce mutual coupling comprises V-shaped conducting plates extending between said rectangular waveguide elements and protruding out beyond the open ends of said waveguide elements.

Claim 7

An antenna array as recited in claim 3 wherein reflecting plates flare out at angles from the open ends of said waveguide elements to define a horn into which said open ends radiate.

Claim 8

An antenna array as recited in claim 1 wherein said predetermined amplitude distribution curve has the shape of the dashed line shown in FIG. 7 and wherein said predetermined phase distribution curve has the shape of the dashed line shown in FIG. 8.

Claim 9

An antenna array as recited in claim 1 wherein said slots include a first set of said slots being coupled to said waveguide in a first manner and a second set of said slots being coupled to said waveguide in a second manner.

Claim 10

An antenna array for generating a shaped beam comprising, a waveguide provided with a series of dumbbell slots positioned along the centerline of a broad face thereof said series being composed of first and second sets of slots, said first set of slots being positioned in the middle of said waveguide with respect to the longitudinal dimension thereof, the slots of said first set being located on the centerline of said waveguide and being coupled thereto by a conductive post positioned opposite each slot of said first set perpendicular to the broad face of said waveguide, a conductive plate mounted within said waveguide opposite each slot of said first set to provide capacitive impedance at the slots to resonate with the inductive impedance provided by the corresponding post, said second set of slots being positioned symmetrically on each side of said first set as respects the longitudinal dimension of said waveguide, said second set being coupled to said waveguide by being offset laterally from the centerline thereof.

Claim 11

An antenna array for generating a shaped beam comprising, a waveguide provided with a series of dumbbell slots positioned along the centerline of a broad face thereof said series being composed of first and second sets of slots, said first set of slots being positioned in the middle of said waveguide with respect to the longitudinal dimension thereof, the slots of said first set being located on the centerline of said waveguide and being coupled thereto by a conductive post positioned opposite each slot of said first set perpendicular to the broad face of said waveguide, a conductive plate mounted within said waveguide opposite each slot of said first set to provide capacitive impedance at the slots to resonate with the inductive impedance provided by the corresponding post, said second set of slots being positioned symmetrically on each side of said first set as respects the longitudinal dimension of said waveguide, said second set being coupled to said waveguide by being offset laterally from the centerline thereof.

Claim 12

An aircraft guidance antenna system comprising a first waveguide provided with a series of dumbbell slots positioned along the centerline of a broad face thereof, said series being composed of a first set of slots positioned in the middle of said first waveguide with respect to the longitudinal dimension thereof, said first set of slots being located on the centerline of said first waveguide and coupled thereto by a conductive post positioned opposite each slot of said first set perpendicular to the broad face of said first waveguide, a conductive plate mounted within said first waveguide opposite each slot of said first set to provide a capacitive impedance at the slots to resonate with the inductive impedance provided by the corresponding post, a second set of slots positioned symmetrically on each side of said first set as respects the longitudinal dimension of said first waveguide, said second set being coupled to said first waveguide by being offset laterally from the centerline Thereof, a second waveguide provided with slot configuration and coupling identical to said first waveguide positioned collinearly with respect to said first waveguide, a cylindrical parabolic reflector positioned opposite said slots with its axis parallel to the longitudinal dimensions of said waveguide sections, and walls of absorbing material extending out from each end of said reflector past the remote ends of said first and second waveguides.

Claim 13

An aircraft guidance antenna system comprising a first waveguide provided with a series of dumbbell slots positioned along the centerline of a broad face thereof, said series being composed of a first set of slots positioned in the middle of said first waveguide with respect to the longitudinal dimension thereof, said first set of slots being located on the centerline of said first waveguide and coupled thereto by a conductive post positioned opposite each slot of said first set perpendicular to the broad face of said first waveguide, a conductive plate mounted within said first waveguide opposite each slot of said first set to provide a capacitive impedance at the slots to resonate with the inductive impedance provided by the corresponding post, a second set of slots positioned symmetrically on each side of said first set as respects the longitudinal dimension of said first waveguide, said second set being coupled to said first waveguide by being offset laterally from the centerline Thereof, a second waveguide provided with slot configuration and coupling identical to said first waveguide positioned collinearly with respect to said first waveguide, a cylindrical parabolic reflector positioned opposite said slots with its axis parallel to the longitudinal dimensions of said waveguide sections, and walls of absorbing material extending out from each end of said reflector past the remote ends of said first and second waveguides.