Abstract: A modular feed system for a phased array antenna is disclosed. Several contiguous radiative elements in a row (or column) are grouped together by a module network to form a linear array module having two inputs. Excitation of one input produces a constant even distribution at the module output, while excitation of the second input produces a linear odd distribution. The module is adapted to approximate both the average value as well as average slope of a segment of an ideal linear array distribution. A network interconnects a plurality of modules to provide independent sum and difference distributions producing low array pattern sidelobes.

Abstract: A wideband shaped beam antenna having steep beam edge slopes in one plane is disclosed. An optical multiple beam antenna such as a geodesic lens antenna, a Luneberg lens or a circular folded pillbox, is coupled at selected points to a feed system having a power divider and phasing control. Coupling of the feed system to the optical multiple beam antenna is effected with a power transition having a wide frequency bandwidth and a capability of conducting high power levels. To shape the beam further, selected beams may be amplitude weighted. An aperture control device such as an E-plane sectoral horn, is attached when required, to narrow the beamwidth in the E-plane. By overlapping multiple beams of the optical multiple beam antenna in accordance with the invention, a sector beam having a constant position and constant steep edge slopes over an octave frequency bandwidth is obtained.

Abstract: A closed loop RF power amplifier output correction circuit is disclosed, for providing closed loop continuous amplitude and phase correction of solid state amplifiers. The circuit includes a two channel RF solid state high power amplifier whose inputs are fed through two control phase shifters and whose outputs are combined in a hybrid junction. A reference signal is provided, which the power amplifier must duplicate in amplitude and phase. A coupling and comparision circuit compares the reference signal and the amplifier output signal and provides an error signal representative of error power. Digital circuitry is provided which takes only relative error power measurements and nulls the error by adjusting the control phase shifters in a closed loop.

Abstract: An electrically scanned phased array with low sidelobes and tapered aperture illumination is disclosed. The array is fed by a uniform corporate feed network (55) and includes a main array aperture formed by main radiating elements (72-75) and first and second ancillary arrays formed by ancillary radiating elements (70-71) and (76-77). For a linear aperture, the outputs from the feed network (55) are phase shifted to steer the beam to one of the available beam locations, and coupled to corresponding ones of the main array radiating elements (72-75) and the ancillary array radiating elements (70-71or 76-77). The beam steering phase shifts invoke uniform phase gradients between the elements of the respective array, and bi-state phase correctors (85-88) are provided to correct for phase gradient discontinuities across the main and ancillary array apertures.

Abstract: An optical limited scan antenna system is disclosed. The invention is a dual lens type array antenna system with a small array feed network. The system includes a bootlace-type microwave aperture lens with an array of radiating elements arranged along the linear aperture and an array of pickup elements arranged along the curved inner surface, an intermediate optical corrective lens, a feed array for illuminating the corrective lens with a source distribution, and with a power divider and phase shifters arranged to drive the feed array. The corrective lens is circularly symmetric (spherically symmetric in the three-dimensional case), and its radially varying dielectric constant is such that a point source on its surface is focused to an image point on the inner surface. The pickup elements on the curved surface of the aperture lens are coupled to corresponding radiating elements on the linear aperture.

Abstract: An antenna of the geodesic lens type is disclosed. The antenna structure is based on optical principles and provides wide angle scanning of a narrow base. The exact shape of the domed structure is found by solving an integral equation and results in nearly perfect focus in the scan plane. A dielectric loaded flared horn is attached to the feed circle of the domed structure and focusses energy in the plane orthogonal to the scan plane. The cross sectional shape of the outer curvature of the dielectric is elliptical. Since the structure is circularly symmetrical, constant beam shape, wide angle scanning, and a rapid scan rate are possible.

Abstract: A phased array antenna system is disclosed for scanning a narrow beam over a limited angular sector with near optimum performance while using the minimum number of active elements. An input corporate feed is coupled to a "thinned" array of phase shifters. Each phase shifter is coupled to one of a plurality of lossless periodic matrix sub-array feed networks. Radiating elements are coupled in periods such as three elements per period. The output of each phase shifter is selectively coupled to the array of radiating elements within its period and to elements in adjacent periods as well. Such an array permits a plurality of overlapping main beams having low side lobes and grating lobes.