Abstract: A quadrifilar helix antenna system that is wound with a helical structure that changes pitch towards top of the antenna. An exemplary antenna system has first and second bifilar helical loops that each comprise a pair of orthogonal windings disposed around a common central axis. Each loop has a winding pitch that varies along the axis to achieve backlobe radiation suppression from the antenna system. First and second terminals are coupled to respective top ends of the bifilar helical loops. The terminals may be fed in phase quadrature by a quadrature hybrid. The antenna system may also include short circuit coupled to respective bottom ends the first and second bifilar helical loops. The antenna system is preferably used in vehicle-to-satellite mobile communication applications.

Abstract: A microstrip antenna includes an annular conducting element spaced by a dielectric element from a conducting ground plane and radiating circular polarization in a conical elevation pattern. A central whip antenna may be located on the axis of the annular-shaped element. Another microstrip antenna having an annular conducting element may be dielectrically spaced from the first-mentioned annular conducting element that comprises the ground plane for the second annular-conducting element.

Abstract: A dual frequency antenna feed includes colinear axially spaced coaxial and circular waveguide cavities separated by a conducting portion having a high frequency rectangular waveguide therein extending radially outward. The coaxial cavity includes a tubular inner conductor having a polarization rotator connected to the rectangular waveguide for propagating high frequency energy. Four small coaxial transmission lines equiangularly disposed about the cavity axes and terminating in probes about a quarter wavelength from the end of each cavity intercouples the circular and coaxial cavities. The end of the coaxial waveguide cavity forms an aperture for high frequency energy from the conducting inner tube and for the low frequency energy from the region between the conducting inner tube and the cylinder surrounding the outside of the cavity. The radiating aperture is surrounded by a set of concentric conducting rings.

Abstract: A microwave lens broadens the radiation pattern of an antenna feedhorn so as to result in improved illumination of the reflector surface. The lens, constructed of dielectric material in the shape of a half-torus, provides feed radiation patterns suitable for use with deep paraboloidal reflectors, typically ones having focal-length-to-diameter ratios between 0.25 and 0.35.

Abstract: A flat face annular grooved metal surface surrounds a circular waveguide opening coupled to a small dipole radiator which excites the circular waveguide in its fundamental propagating mode (TE.sub.11). The dipole is arranged to rotate about its axis by means of an extension of its inner conductor, which forms a simple probe in a section of rectangular waveguide situated behind the circular waveguide. A dielectric shaft is fastened to the inner conductor and is brought to the outside of the rectangular waveguide where it is connected to a small motor. The motor is arranged so that it may be actuated remotely by any of several circuits. The dipole may be before the corrugated plate with bent arms. A pair of dipoles may be arranged perpendicular to each other with two separate coaxial connector antenna feed outputs for direct attachment to coaxial-type low-noise amplifiers.