Abstract: Method for coherently combining signals received from two widely separated antenna apertures (204, 206). The method includes positioning a first antenna aperture (204) at a first location spaced apart a distance with respect to a second location of a second antenna aperture (206). A distance between the first antenna aperture and the second antenna aperture is selected to be at least a plurality of wavelengths at a predetermined operating frequency of the first antenna aperture and the second antenna aperture. An antenna beam or pattern (208, 210) from each antenna aperture (204, 206) is directed toward a target (212) positioned at a location remote from the first antenna aperture and the second antenna aperture. Adaptive digital processing (416) is then used to coherently combine the signals independently received by each aperture from the common source.

Abstract: A antenna array (20) includes a plurality of periodic or aperiodic arranged sub-arrays (22). Each sub-array (22) includes a plurality of antenna elements (32) arranged in the form of a spiral (30). The sub-arrays (22) can comprise various spiral shapes to provide the required physical configuration and operational parameters to the antenna array (20). The elements (32) of each sub-array (22) are arranged to minimize the number of such elements (32) that intersect imaginary planes perpendicular to the spiral and passing through the spiral center. Such an orientation of the elements (32) minimizes grating lobes in the antenna pattern.

Abstract: The invention concerns a quadrifilar helix antenna that has four orthogonal conductive elements helically wound around a common axis. Each of the conductive elements can have between 3 to 7 turns about the common axis at a pitch of between 45 to 65 degrees. Further, each turn has a diameter of about 0.13 wavelengths to 0.27 wavelengths. A feed coupler excites each of the orthogonal conductive elements in phase quadrature at a feed point located at a first end of the antenna adjacent to a ground plane. The resulting antenna can have an axial length of about 2.3 wavelengths to 6.9 wavelengths. Unlike conventional quadrifillar helix antennas, an opposing end of each of the conductive elements distal from the feed point forms an open circuit. The antenna configured as described can have a peak gain on horizon when the common axis is oriented vertically.

Abstract: The invention concerns a quadrifilar helix antenna that has four orthogonal conductive elements helically wound around a common axis. Each of the conductive elements can have between 3 to 7 turns about the common axis at a pitch of between 45 to 65 degrees. Further, each turn has a diameter of about 0.13 wavelengths to 0.27 wavelengths. A feed coupler excites each of the orthogonal conductive elements in phase quadrature at a feed point located at a first end of the antenna adjacent to a ground plane. The resulting antenna can have an axial length of about 2.3 wavelengths to 6.9 wavelengths. Unlike conventional quadrifillar helix antennas, an opposing end of each of the conductive elements distal from the feed point forms an open circuit. The antenna configured as described can have a peak gain on horizon when the common axis is oriented vertically.

Abstract: A antenna array (20) includes a plurality of periodic or aperiodic arranged sub-arrays (22). Each sub-array (22) includes a plurality of antenna elements (32) arranged in the form of a spiral (30). The sub-arrays (22) can comprise various spiral shapes to provide the required physical configuration and operational parameters to the antenna array (20). The elements (32) of each sub-array (22) are arranged to minimize the number of such elements (32) that intersect imaginary planes perpendicular to the spiral and passing through the spiral center. Such an orientation of the elements (32) minimizes grating lobes in the antenna pattern.

Abstract: A slot antenna is disclosed for use in RF broadcasting. The antenna includes an elongated longitudinally extending hollow mast surrounding a longitudinal axis. An array of longitudinally spaced slots are formed in the mast for radiating electromagnetic energy therefrom. A coupler bar is associated with each slot. Each coupler bar is located within the mast between the ends of the associated slot for coupling electromagnetic energy from within the mast and developing with the slot a slot-coupler reactance. Tuning means is associated with each slot. Each tuning means is longitudinally spaced from the associated slot. Each tuning means extends inwardly from the mast toward the longitudinal axis for tuning the antenna to reduce the slot-coupler reactance.