Abstract: An array of collinear coaxial lines utilizes standard size brass tubing with brass rods inserted therein to establish each half-wavelength coaxial section. A coupler positioned between each half-wavelength section has an outer conductor supports and through passages for the inner conductor. Inner conductors of the transmission line elements are soldered to the outer conductors of the respective adjacent transmission line elements so that all elements are excited with the same phase and polarity. Air dielectric between the inner and outer conductors provides a transmission line wavelength equal to that of free space so that the length of each element in the array is a free space half-wavelength long, thereby providing an antenna gain greater than that achievable with transmission lines having solid dielectric supporting the inner conductor.

Abstract: A system for adaptively positioning nulls in the pattern of an antenna utilizing an auxiliary antenna in conjunction with a correlation receiver to determine the gain in amplitude and phase of the antenna pattern at the location of the interfering source. This gain is then utilized with the known gain at the peak of the main lobe of the antenna to compute coefficients of sinusoidal perturbation functions applied to the phase function of the antenna to establish a null in the direction of the interfering source.

Abstract: An apparatus and method for scanning a circular array through 360.degree. with tapered aperture illumination function to achieve radiated beams with desired sidelobe levels. A switching matrix selects a predetermined number of active elements from the total number of elements disposed about the circle to form a sub-array. To this sub-array a variable amplitude distribution network is coupled to establish excitations at each active element in accordance with a desired amplitude distribution function.

Abstract: An antenna and a method for obtaining predetermined far field antenna patterns is disclosed. Empirical adjustments of a focal region feed system provides for the compensation of tolerance or other imperfections of the antenna to achieve the desired far field pattern. An element of the feed system is adjusted when the antenna is angularly positioned, with respect to a receiving element in the far field, which corresponds to the location of the element in the feed array. A desired far field pattern may also be achieved by illuminating the antenna aperture, either simultaneously or sequentially, by several plane waves, the amplitude and incident angles of which are carefully controlled, measuring the phase and amplitude of the focal region distribution caused by this illumination, and designing the feed system to establish a focal region distribution that is the complex conjugate of that measured.

Abstract: A feed system for scanning focal plane antenna systems with which a variable focal spot illumination may be achieved within the focal region of a primary antenna over a limited scanning sector is disclosed. An array of collector elements positioned to receive radiation from a scannable feed antenna is coupled to an array of radiator elements positioned in the focal region of the primary antenna, the positioning of the radiator and collector elements are such that the focal spot illumination is caused to vary with the scan angle of the antenna.