Abstract: A pair of diffraction gratings are disposed between a fiber and a waveguide carried by a substrate. The gratings each have a common spatial frequency component that couples light between the fiber and the waveguide. Light from the gratings establish first and second components of an electromagnetic field that extend into the substrate. The gratings are constructed and positioned to cause the first and second components to be of substantially equal amplitude and opposite phase thereby inhibiting a coupling of light into the substrate.

Abstract: A hollow cylinder that has a permittivity greater than the permittivity of air is coaxially disposed within a waveguide with the proximal end of the cylinder coplanar with one end of the waveguide. The cylinder has a metal clad surface wherein a plurality of tapered slots that are narrowest at the proximal end of the cylinder and widest at the distal end thereof. The slots are coupled to respective amplification devices, thereby causing the waveguide to be terminated in an impedance substantially equal to impedances of the devices connected in series. Microwave power is transmitted through the waveguide via propagation of a wave in the TE.sub.01 mode. When the wave propagates to the cylinder, the power is transmitted to the devices via the electric fields within the slots at the proximal end of the cylinder. The wave propagates from the cylinder in response to the power being provided by the devices.

Abstract: A radar antenna includes a plurality of radiators disposed near the focal point of a parabolic reflecting surface. The radiators are coupled to a sector horn waveguide via a plurality of phase shifters and a Butler matrix. The sector horn is concurrently excited in H.sub.10 and H.sub.12 modes of propagation to provide excitation to the radiators. Radiated energy from a radiator propagates to the reflecting surface and is reflected therefrom.

Abstract: Electronically steered antenna system is provided by placing a panel of dielectric material with specific thickness and dielectric constant spaced forward of an array of piezoelectric transducers. These piezoelectric transducers present a refelective surface. High frequency wavefronts are transmitted toward the dielectric panel and pass on to the reflective surface. The phase of the reflected waves depends upon the spacing of the reflective surfaces from the panel. A change in this spacing is provided by electrical control signals being applied to the piezoelectric transducers.

Abstract: First and second diffraction gratings have a common fundamental spatial frequency. A coupling assembly is formed by connecting the gratings together with bars of the first grating at an angle of approximately 10.sup.-3 radians to bars of the second grating. The coupling assembly is mounted upon a waveguide carried by a substrate. A fiber is moved to a multiplicity of locations on the coupling assembly while light is transmitted through the waveguide. The fiber is fixedly connected to the coupling assembly at a location where there is a maximum amount of the light coupled from the waveguide to the fiber, whereby the fiber and the substrate form a sandwich that includes the coupling assembly and the waveguide. An etching process is used to remove parts of the coupling assembly that are not within the sandwich.

Abstract: A spectrum reuse antenna system is described for transmitting orthogonally polarized RF waves at one frequency band to a satellite and for receiving orthogonally polarized RF waves from a satellite at a second frequency band through a common antenna. A local generator provides a first control signal which varies as a function of the typical rotation of the polarization of a transmitted wave at the one frequency band travelling through the ionosphere. The local generator also provides a second control signal which varies as a function of the typical rotation of the polarization of a received wave at the second frequency band travelling through the ionosphere. A driven means responsive to the first control signal causes a rotation of the polarization of the transmitted waves to correct for Faraday rotation in the ionosphere and a driven means responsive to the second control signal causes rotation of the polarization angle of the antenna system for the received waves to correct for the Faraday rotation.

Abstract: A moveable mask with a pin hole therethrough is disposed between a source of an object beam and a holographic recording medium. The pin hole limits the angular range of rays of the object beam transmitted to the medium, thereby preventing intermodulation distortion caused by rays of the object beam that have large angles therebetween. The mask may be moved to cause all of the rays of the object beam to pass through the pin hole, whereby a hologram is recorded.

Abstract: A holographic recording of a plurality of rows of informational elements, which may represent a binary number, is successively illuminated by each of a plurality of light sources, where the number of light sources equals the number of rows of elements. In response to the successive illumination, a holographic reconstruction of the elements is projected upon photodetectors disposed along a line in a projection plane. The illumination may be instead by a deflected beam having an angle of incidence with the recording which changes at a vertical scan rate. In response to the deflected beam, a holographic reconstruction of horizontal lines of the elements are successively projected upon the photodetectors.

Abstract: A circular array of twelve light sources transmit light to an eye. A spherical shape of the cornea of the eye is indicated when light reflected therefrom appears to be transmitted from twelve virtual light sources disposed along a circular path within the eye. Correspondingly, an aspherical shape of the cornea is indicated when the virtual sources appear to be disposed along an acircular path within the eye. The array may be disposed within a light reflecting groove which collects ambient light which is transmitted to the eye. A reflection of the collected light appears to be a ring of light which connects the virtual sources.

Abstract: An opaque open-ended cylindrical tube, with a flange on one end, has its other end connected to a surface of a platform with the axis of the cylinder normal to the surface. When rays of the sun are substantially normal to the surface, a lens causes a concentrted illumination of a group of tracking photocells carried on the surface within the cylinder. In response to the concentrated illumination, the tracking photocells provide signals that cause the platform to rotate in a direction that maintains the surface substantially normal to the rays of the sun. Additionally, outside of the cylinder and adjacent thereto, a group of acquisition photocells are shielded by the flange from the sun when the rays thereof are substantially normal to the surface. When there is a large angle between a normal to the surface and the rays of the sun, the acquisition photocells provide signals that cause the platform to rotate in a direction that reduces the angle.

Abstract: A multimode coupling system for coupling symmetrical waveguide mode signals and two or more tracking asymmetrical waveguide mode signals includes a funnel-shaped coupler with a plurality of coupling apertures located in the side wall thereof. A first four of these side wall apertures lie in a first common plane at a given distance from the small aperture end of the coupler. A second four of these apertures lie in a second common plane a second given distance from the small aperture end of the coupler. A first coupling circuit is provided between the first group of side wall apertures and an asymmetrical mode terminal, and a second coupling circuit is provided between the second four apertures in the second plane and a second asymmetrical mode terminal.

Abstract: A solid cylindrical recording medium is axially rotatable within a cavity in a transparent block, the medium and the cavity being complementary in shape. The medium and the block have substantially equal indexes of refraction whereby the medium does not refract light transmitted thereto through the block. Transmitted to the medium (through the block) is an object beam, representative of an image, and a reference beam, whereby the medium is exposed and a volume hologram of the image is recorded. A multiplicity of volume holograms of images may be recorded by rotating the medium with respect to the reference beam after each of a multiplicity of exposures.

Abstract: A fuel insertion door forms a portion of the top of a fire box of a wood burning stove. The stove additionally includes a viewing door which closes to cover an opening in the front of the fire box. When the fuel insertion door is closed, a tab extending therefrom overhangs the front of the fire box to maintain a closure of the viewing door.