Abstract: Disclosed is a method and apparatus for improving airborne vehicle tracking and guidance systems by reducing boresight error induced by polarization of the RF energy impinging on the vehicle radome. The radome wall is formed with a taper which gradually increases from the base near the vehicle antenna to the tip according to a disclosed formula which accounts for frequency, incidence angle, look angle, and the dielectric constant of the radome material. This taper of the radome minimizes the crossplane boresight error component magnitude which is polarization sensitive and produces a polarization insensitive inplane boresight error component. Also disclosed is a method of electronically compensating such radomes for boresight error where the radome boresight error data accumulated during testing is digitized and processed for compensating data in the vehicle electronic system to provide compensated tracking data for the vehicle guidance system.

Abstract: A direct-sequence spread-spectrum communication system having a receiver that despreads a received signal that has been modulated with a pseudonoise code generated by a linear feedback shift register. The receiver despreads the received signal by multiplying it with a limited number of delayed replicas of the received signal. Despreading is thus performed without need for a locally generated pseudonoise code or a synchronizing clock.

Abstract: An optical power summing apparatus that allows a multiplicity of optical signals to be combined with minimal signal transmission loss. A single photodiode simultaneously receives all of the input signals to perform a summation of signal powers. Alternative embodiments of the apparatus use either a tightly packed bundle of etched optical fibers or a converging arrangement of optical waveguides on a dielectric substrate to focus the optical signals onto the base region of a single photodiode.

Abstract: The fiber optic combiner/splitter is a positive and negative axicon combination which can convert a ring-shaped beam into a solid beam. The positive half of the axicon is effectively a plano-convex lens where the convex surface is generally a shallow cone. The flat surface of the lens abuts each end of an array of single mode fibers which are arranged in a ring configuration around a support member. The negative half of the axicon is effectively a plano-concave lens which is complementary to the positive lens. The focused beams from the positive half of the axicon are combined to form a single beam which is then directed into a single optical fiber. For conversions in the reverse direction, light is taken from a single multimode fiber and expanded into a ring-like pattern. The ring of light is picked up by the ring of single mode fibers. Each single mode fiber receives an equal amount of optical energy or power to provide good efficiency in splitting of the multiplexed beam.

Abstract: A laser fabricated from a substrate having top and bottom surfaces. A first stack of mirror layers of alternating different refractive indices are formed upon the substrate top surface. An active layer defining a mesa is formed on top of the first stack of mirror layers. A second stack of alternating different refractive indices mirror layers are formed upon the active layer mesa. A current confinement layer is formed about the side of the active laser mesa. A first contact is formed upon the substrate bottom surface while a second contact is formed upon a portion of said active layer remote from the active layer mesa.

Abstract: A process is described for enhancing superconductor characteristics by application of strong magnetic and/or electric fields to the constituent component materials from which ceramic superconductors are being formed and during the time that these superconductors are being synthesized. This process has particular applicability to the production of superconducting oxide ceramics such as the cuprates. The required magnetic fields are on the order of 1-10 tesla and the required electric fields are on the order of 0.1-1 MV/cm. The fields act as ordering mechanisms and induce grain orientation. The magnetic field aligns the magnetic moment of the grains. The electric field induces electric polarization in the grains and then aligns them. The superconducting structure formation occurs during the sintering, cooling and annealing phases of the fabrication process. Superconductivity is strongly affected by the oxygen stoichiometry in the lattice elemental cell. Applied electric fields cause elongation of the unit cell.

Abstract: An interconnection assembly for connecting a unit under test to a testing unit including a plurality of spaced parallel circuit cards, the interconnection row assembly comprising of connector terminals adjacent the outer edges of each circuit card, an interface test adapter unit containing signal relaying circuitry for relaying the appropriate signals back and forth between the test unit and the unit under test, the interface unit having connectors for connection to the unit under test, and an outer face carrying connector terminals for connection to respective connector terminals on the circuit cards. A coupling mechanism releasably couples the units together with the outer face of the adapter unit facing the outer edges of the circuit cards.

Abstract: A fiber optic power coupling device such as a power summer, power divider or star coupler comprises a segment of multimode optical fiber having an input mirror at one end and an output mirror at the opposite end. One or more inputs at the input end of the fiber segment direct an equivalent number of input, intensity modulated light signals into the fiber and one or more outputs at the output end direct a corresponding number of output signals out of the fiber. Where there is one input and a plurality of outputs, the device acts as a power divider. Where there are a plurality of inputs and one output, the device acts as a power summer. Where there are a plurality of inputs and a plurality of outputs, the device acts as a star coupler.

Abstract: A multiple pole optical bandpass filter comprises at least two input filter elements each having an input at one end and an output at the opposite end, and an output filter element having at least two inputs at one end coupled to the respective outputs of the input filter elements, and an output at the opposite end. Each of the filter elements comprises a segment of multimode optical fiber of predetermined length having mirrors at its opposite input and output ends. An intensity modulated light signal is provided at one of the input filter element inputs, while the same signal shifted by 180 degrees is provided at the other input filter element input.

Abstract: A semiconductor laser for emitting light transverse to the direction of current injection. The laser is fabricated from a substrate having planar top and bottom surfaces and an aperture formed therebetween. An optical cavity, formed upon the substrate top surface and aligned with the aperture, has co-planar top and bottom surfaces with dielectric mirrors formed thereupon. Contacts are formed adjacent the optical cavity for conducting current through the optical cavity in a direction substantially parallel to the optical cavity top and bottom surfaces. Current confinement layers are disposed in intimate contact with the optical cavity for confining current flowing in the optical cavity along a predetermined path extending between the contacts.

Abstract: A vehicle-mounted passive synthetic aperture system for locating sources of electromagnetic radiation having a given wavelength .lambda.. The system includes first and second receiving antennas, a phase sensitive receiver and a signal processor. The first and second antennas are mounted to a vehicle and spaced apart from each other in the principle direction of motion associated with the vehicle. The first and second antennas respectively provide first and second received signals in response to a wavefront of electromagnetic radiation having the given wavelength .lambda.. The phase sensitive receiver is coupled to the first and second antennas and responds to the first and second received signals by providing a phase difference signal that indicates a phase difference .phi. between the wavefronts of the radiation of the given wavelength received by the respective first and second antennas when the received radiation is radiated spherically from its source. The speed of the vehicle also is measured.

Abstract: A dual-path, multicontact connector for a printed circuit board includes two perpendicular groups of contacts and a plurality of internal switches which permit conductivity to be selectively established between one or more pairs of contacts or between either contact of each pair and an electrical circuit on the circuit board. Each contact of a contact pair is included in a respective group of contacts. The perpendicular arrangement of the contact groups allows one group of contacts on the dual-path connector to engage corresponding contact groups on adjacent abutting dual-path connectors. Selective operation of the internal switches in a series of abutting connectors can provide alternate conductive pathways to electrical circuits on any board through the contacts of one or more adjacent connectors.

Abstract: An antenna-radome structure that functions as a self-referencing interferometer, including a radome having a leading edge and including a plurality of longitudinally disposed slabs of dielectric material having a front edge adjacent the leading edge of the radome; and a corresponding number of antennas disposed normal to the longitudinal axis of the radome and respectively embedded in or placed on the surface of each corresponding dielectric slab. Each antenna is located at a distance from the front end of the corresponding dielectric slab corresponding to a maximum of intensity in an intensity fringe pattern produced by interference between free space waves of a predetermined frequency incident upon the dielectric slab and waves guided by the dielectric slab in response to the incident waves. The thickness of each dielectric slab is tapered for reducing sidelobe levels in the far field pattern of the antenna.

Abstract: A vehicle-mounted passive synthetic aperture system for locating a source of electromagnetic radiation having a given wavelength .lambda.. The system includes first and second receiving antennas, a phase sensitive receiver and a signal processor. The first and second antennas are mounted to a vehicle and spaced apart from each other in the principle direction of motion associated with the vehicle. The first and second antennas respectively provide first and second received signals in response to electromagnetic radiation having the given wavelength .lambda.. The phase sensitive receiver is coupled to the first and second antennas and responds to the first and second received signals by providing a phase difference signal that indicates a phase difference that is proportional to the difference between the respective ranges from the first and second antennas to the source of the received radiation when the received radiation is radiated spherically from its source.

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Abstract: A method and apparatus for measuring radiant energy scattering characteristics of a test panel of dielectric material over a sphere are disclosed. The test panel is supported on a turntable at a position on the axis of the turntable. The turntable has a first antenna radially mounted thereon for rotation therewith and directed toward the position of the supported test panel. A second antenna is mounted for selective positioning along a circular arc within a plane that includes the axis of the turntable, which arc extends at least ninety degrees from said axis, wherein the second antenna is radially directed toward the position of a test panel that is axially supported on the turntable at all positions along said arc. The test panel support is rotated with respect to the turntable to selectively position the test panel at a predetermined incidence angle with respect to the first antenna.

Abstract: High stability thin film resistors are made from an alloy comprising selected portions of nickel, chromium, and gold selected in a ratio to provide the desired temperature coefficient of resistance (TCR). The resistors are made by co-depositing gold with the nickel chromium alloy by a flash evaporation process. The evaporation process is carried out by feeding a nickel chromium wire, having a gold wire extending therealong to provide the desired composition, onto a heated tungsten strip within a vacuum system with substrates disposed in a position to obtain uniform deposition of the evaporated material thereon.

Abstract: High stability thin film resistors are made from an alloy comprising selected portions of nickel, chromium, and gold selected in a ratio to provide the desired temperature coefficient of resistance (TCR). The resistors are made by co-depositing gold with the nickel chromium alloy by a flash evaporation process. The evaporation process is carried out by feeding a nickel chromium wire, having a gold wire extending therealong to provide the desired composition, onto a heated tungsten strip within a vacuum system with substrates disposed in a position to obtain uniform deposition of the evaporated material thereon.

Abstract: A system for determining the position of a ship in relation to predetermined positions on the ocean floor is disclosed. A plurality of first acoustic addressable transponders and a plurality of second acoustic addressable transponders are respectively located at first and second sets of predetermined positions on the ocean floor. Each of the acoustic transponders transmits an acoustic ranging response and identification signal in response to receipt of an acoustic ranging interrogation signal. First and second buoy communications systems are located on first and second buoys respectively moored to the ocean floor in the vicinity of the first and second pluralities of acoustic transponders.