Abstract: A small volume, broad beam antenna is disclosed. The antenna has four cavity backed elements. Each of the elements is triangular shaped and is mounted such that the narrow portions of the triangular elements are over the center of the cavity.

Abstract: A low cost, broadband, broadbeam antenna. The radiating elements of the antenna are two spiral conductors mounted over a cavity. Inside the cavity, strips of RF absorber and a metal shim are located. Resistive damping at the ends of the sprial conductors is provided by discrete resistors. A dielectric lens covers the spiral conductors.

Abstract: An antenna system comprising a vertical monopole antenna coupled to a first feed on a ground plane conductor and a dipole antenna comprising a plurality of horizontal dipole antenna elements coupled to a corresponding plurality of feeds on the ground plane conductor, the plurality of dipole antenna elements being disposed about the first feed. The vertical monopole antenna comprises a plurality of monopole antenna elements, the plurality of monopole antenna elements and the plurality of dipole antenna elements being alternately radially disposed about the first feed.

Abstract: An array antenna is provided wherein each adjacent pair of a plurality of antenna elements in such array antenna have a common, conductive wall having a castellated radiating edge. Radio frequency energy resistive material is disposed within slots formed in the radiating edge. With such arrangement, electrical coupling between the adjacent pair of antenna elements is reduced thereby improving the gain of the antenna at the lower frequency operating band of the antenna. Further, the electric field distribution is redistributed by the slotted radiating edge from a cosine distribution associated with a linear edge to a more flattened, uniform distribution to increase the effective aperture of the element in the H-plane.

Abstract: A coaxial cable for coupling radio frequency (RF) signals therethrough with a predetermined, nominal attenuation comprising a center conductor selected to maintain the attenuation of the coaxial cable at substantially the nominal attenuation substantially independently of the frequency of the RF signals over a predetermined frequency range, such as from 2 to 18 GHz. In a preferred embodiment of the invention, the center conductor is selected having a nominal volume resisitivity (.rho.) and a nominal permeability (.mu.), with the volume resistivity-permeability product thereof substantially varying inversely with changes in frequency of RF signals coupled through the cable. With such arrangement, a lossy coaxial cable providing substantially constant attenuation over a broad range of frequencies, such as greater than three octaves, is provided having reduced size, complexity and VSWR from conventional lossy cable assemblies comprising a conventional coaxial cable coupled in series with an attenuator.

Abstract: A radio frequency antenna is provided comprising: a waveguide section; first means for establishing radio frequency energy in such waveguide section having a first linear polarization with an electric field disposed normal to opposing wide walls of the waveguide section; a planar microwave circuit means, for establishing a second linear polarization having an electric field disposed perpendicular to the electric field of the first linear polarization, such microwave circuit means being disposed within the waveguide between the wide walls and relative to the feed means to provide the first linear polarization and the second linear polarization with substantially coincident phase centers. In a preferred embodiment of the invention, the microwave circuit means includes a strip conductor feed separated from a ground plane conductor by a dielectric, such ground plane conductor having a notch formed therein and fed by the strip conductor.

Abstract: A radio frequency antenna element is provided comprising a waveguide having disposed within and adjacent to a rearward portion of such waveguide a ridge, such ridge having a relatively narrow forward portion and a plurality of feeds, disposed within the waveguide, for coupling energy from a plurality of sources to a relatively wider, rearward portion of the ridge. The waveguide has a pair of opposing, relatively wide upper and lower walls and a pair of opposing, relatively narrow side walls. The relatively wider, rearward portion of the ridge tapers to the narrower forward portion of the ridge in a plane parallel to the upper and lower walls of the waveguide. The narrow portion of the ridge tapers towards one of the wider walls as such ridge extends from the rearward portion of the waveguide to the forward portion of the waveguide.

Abstract: A radio frequency antenna comprising a rectangular waveguide having opposing relatively concave-shaped narrow side wall portions extending from a rear wall of the waveguide structure to an aperture of the antenna element. The separation between the sidewalls, at a distance intermediate the rear wall and the aperture, is greater than the width of the aperture. The waveguide includes a ridge-shaped feed structure extending from the rear wall to the aperture. A pair of ground plane conductors having surfaces each with an edge terminating along an aperture edge of a corresponding one of the sidewalls at the periphery provide a pair of aperture edges. Each one of the ground plane conductors extends for a length greater than .lambda./3 where .lambda. is the wavelength at the lowest operating frequency of the antenna. With such arrangement, an antenna element is provided having a relatively constant beam width over the operating bandwidth of the antenna.

Abstract: A radio frequency antenna including an antenna element having an open-ended waveguide section coupled to a first feed means for establishing radio frequency energy having linear polarization, the electric field vector of such energy being disposed normal to a pair of opposing wall portions of the waveguide. The antenna element includes a microwave circuit means for establishing radio frequency energy having a linear polarization orthogonal to the polarization of the first mentioned radio frequency energy. The microwave circuit includes a dielectric and a conductive sheet disposed over the dielectric; such sheet providing one of the wall portions of the waveguide section. The conductive sheet has an array of notches formed therein, such notches being disposed adjacent the open end of the waveguide section.

Abstract: A radio frequency antenna comprising a waveguide having opposing relatively wide, upper and lower wall portions, a pair of opposing, relatively narrow side wall portions, and a relatively narrow rear wall portion, such portions being connected to provide a cavity having an open end disposed opposite the rear wall portion, the separation between the side wall portions decreasing as such side wall portions extend towards the rear wall portion. The waveguide includes a ridge disposed within the cavity, the decreasingly separated side wall portions of the waveguide being disposed between the ridge and the rear wall portion of the waveguide. The ridge is coupled to a coaxial transmission line. With such arrangement the decreasingly separated side wall portions of the waveguide improve the impedance matching between the coaxial transmission line and the ridged waveguide antenna element, thereby increasing the operating bandwidth of the ridged waveguide antenna element.

Abstract: A radio frequency antenna is provided wherein an array of antenna elements is adapted to establish linearly polarized radio frequency energy. A polarizer means is disposed between the array of antenna elements and free space for converting the linearly polarized radio frequency energy associated with the antenna elements into circularly polarized radio frequency energy in free space, such polarizer means being disposed about a frontal portion and side portions of the array antenna elements. A polarization filter means for rejecting radio frequency energy having a selected linear polarization is disposed between the side portions of the array of antenna elements and the polarizer means. In a preferred embodiment of the invention, the polarization filter is disposed to reject radio frequency energy having a linear polarization, such linear polarization being disposed at an acute angle with respect to the linear polarization provided by the antenna elements.

Abstract: An antenna element for use in the nose section of a small missile is disclosed. The antenna element includes a ground plane and a pair of end fed radiating elements, the free ends thereof being fastened to ground plane. With such arrangement the antenna element fits compactly within the nose section and the ground plane provides a heat sink and structural support for the radiating elements.

Abstract: A radio frequency antenna having a flared, discontinuous slot formed on one surface of a dielectric support structure and a feed formed on the opposite surface of such structure. The feed is disposed across a narrow portion of the slot. A housing having a cavity formed therein is provided. The dielectric support is disposed on the housing over the cavity. The cavity has a conductive wall, or deflective plate, disposed beneath a wide portion of the slot. The effects of the feed and the slot-deflection plate combine to provide a flush-mountable antenna having a cardioid-shaped radiation pattern.