Abstract: A notch filter includes a directional coupler (16) with an input port (17a), coupled output port (17b), coupled 0.degree. (17d) and direct 90.degree. (17c) ports. A cylindrical dielectric resonator (40) is supported by a spacer (58) above a ground plane (14) and dielectric substrate (12). A first microstrip transmission line includes a strip conductor (22) coupled at one end to the coupled 0.degree. port, and extending parallel to a tangent to the edge of the resonator at a central plane (44), terminating in an open-circuit (226). A second transmission line includes a strip conductor (24) coupled to the direct 90.degree. port (17c) and extending parallel to the first transmission line, on the other side of the resonator. The first and second transmission lines each have an electrical length .lambda./4 between the central plane (44) and their open-circuit terminations, to reflect a high current to the plane.

Abstract: An active array antenna for use, for example, in a radar system, includes elemental antennas, each with a T/R module, distributed over a circular aperture. For lowest cost, the aperture is thinned. The T/R modules are operated at maximum output, to achieve maximum DC-to-RF efficiency, and for simplicity. A phase controller controls the phase shift which is imparted by each module to its signal, to form a main beam and its associated sidelobes. A perturbation phase generator portion of a phase controller adds a perturbation phase shift selected, in conjunction with a particular thinning distribution, to form a relatively wide null in the sidelobe structure, in which signal transduction is reduced. In a radar context, this null may be placed on a source of ground clutter or a jammer.

Abstract: A travelling-wave tube (TWT) for a satellite communication system includes a cathode current regulator which compares a sensed I.sub.K signal with a cathode current reference to form an cathode current error signal, and controls the cathode current in response to the cathode current error signal. Helix arc protection is provided by a helix current shut-down, which compares the helix current with a particular reference, and shuts the TWT supply down when helix current flows. Desirable high efficiency TWTs have a small input drive range between maximum TWT output and a defocussed condition, in which beam current flows in the helix. Sudden changes in path attenuation may result in an RF overdrive condition, and cause helix current flow, and undesirably shut down the TWT. A helix current limiter senses the helix current, and compares it with a reference which represents less helix current than that which causes shutdown, to produce a helix current error signal.

Abstract: A device for converting a set of electronic signals that represent an image into a coherent image includes a two-dimensional array of asymmetric Fabry-Perot (ASFP), quantum-well-based optical modulators connected on a pixel-by-pixel basis to a two-dimensional array of drive circuits located on an integrated circuit. Electronic signals received by the integrated circuit cause the pixel drive circuits to change a bias voltage applied across the optical modulator section and, thereby, change the optical properties of the optical modulator section of the device. The two-dimensional array can be used to impart intensity-only, phase-only, or phase-and-intensity variations onto a beam of coherent laser light incident on the array. This coherent image can be used with other optical elements to form optical processing machines and optical storage devices.

Abstract: An arrangement for butt-welding cylindrical sections of large, thin-wall tanks includes a rotatable mandrel with side-by-side sets of radial position adjusters. Each set of adjusters bears on one of the tank sections adjacent the seam, to prevent the sections from sagging out-of-round. The mandrel rotates relative to the welder, so that a continuous seam is formed. A purge chamber is fixed in position behind the seam at the weld head, and is flushed with inert gas. The purge chamber includes a two-sided structure which is contiguous with the cylindrical sections and a circumferential vane to form an open-ended tube-like structure, through which the radial position adjusters pass as the mandrel and cylindrical workpiece sections rotate. The tube-like structure is formed into a chamber by a plurality of movable gates which are controlled to maintain a seal while allowing adjusters to progress through the purge chamber.

Abstract: The electrical length of a strip transmission line structure is adjusted by adding conductive projections from the ground planar conductors which extend in depth toward the strip conductor and in length along the strip conductor. These projections may preferably be formed by inward deformation of the ground planes at the desired locations. In strip transmission lines having the strip conductor positioned between two ground planes, projections are preferably added in aligned pairs with each ground plane providing one of the projections of the pair.

Abstract: A hinge includes a first clevis (30), defining a vee-block support (12) and a first limiter surface (44, 46, 48). A cylindrical hinge shaft is supported by the vee-block (12). A second clevis (140) is affixed to the shaft, whereby the second clevis may rotate in response to torques. The second clevis has a limiter surface (148) which coacts with the first limiter to limit rotation of the shaft and second clevis past the deployed state. The second clevis (140) has a cam follower (158) at a predetermined distance from the axis of rotation (2). A cam (100, 104) affixed to the first clevis (30) rotates about a cam axis (3'). The deployed-state engagement between the cam and the follower snugs one end of the shaft into the vee-block, while the rotation limiters snug the other end. A rotational driver (50, 54, 70, 75, 90, 110) urges the cam (100, 104) to rotate in a direction which tends to move the second clevis (140) from the stowed state toward the deployed state.

Abstract: A spacecraft (10) includes N paralleled power converters (24a, 24b . . . ) for producing current pulses in response to converter synchronizing pulses. The current pulses are integrated (28) to produce an operating direct voltage. The synchronizing pulses are produced in a recurrent cycle by a synchronizer (30). The synchronizer includes a voltage divider (320) with equal series-connected elements (324a, 324b . . . ), each of which is paralleled by a shorting switch (330a, 330b . . . ). A sawtooth signal generator (310) produces a sawtooth signal (312), which is applied in common to each of a plurality of comparators (332a, 332b . . . ). The voltage divider (320) is connected across a reference voltage (318), to produce a plurality of reference voltages at the taps (328a, 328b). Each comparator (332) compares the sawtooth ramp (314) with one of the reference voltages, so that the comparators trigger in sequence as the ramp rises. The comparators trigger at times corresponding to equal phase increments of 360.

Abstract: An optical demultiplexer includes an electrooptic modulator (410) which modulates a beam of light (418) in response to frequency-multiplexed radio-frequency (RF) information signals, to produce diverging beamlets of light (420). The diverging beamlets are separated by a spatial separator arrangement (426), and each beamlet (420), including the information of its RF carrier, is coupled to a separate optical detector (428). The detector (428) can extract amplitude modulation from the signal. In order to reconstruct the RF signal as well as the amplitude modulator, an optical "local oscillator" signal (OLO) is coupled to each detector together with its information signal. Signal loss due to vibration or misalignment is avoided, and heterodyne mixing efficiency is maximized in an embodiment of the invention, by propagating the OLO and information signals through a single-mode optical fiber to the detector.

Abstract: A radar system transmits dispersed pulses, and receives echoes from targets. The echo signals are digitized and applied over a number of signal paths. In each signal path except one, the digitized signal is multiplied by one of a plurality of differential exponential signals, for converting the echo signal of different exponential signals, for converting the echo signal in each path to baseband, with the baseband frequency representing a particular Doppler which depends upon the exponential signal. In the one remaining signal path, no multiplier is used, and the echo signal is deemed to be at baseband. The signals in each path are applied through a cascade of a pulse compressor and a range sidelobe suppressor. Since Doppler filtering has not yet taken place, full compression and range sidelobe reduction is not achieved, because of extraneous pulse-to-pulse phase shifts.

Abstract: A semiconductor device having a metalized via hole used when mounting and connecting semiconductor chips, such as microwave chips, digital chips, analog chips and the like, on a top portion of a metalized carrier substrate is described herein. Each chip includes electrical circuitry on a top portion thereof with the circuitry connected to one end of a transmission line. Another end of the transmission line is connected to a metalized via hole. The via hole passes from the top portion of the chip to a bottom portion of the chip. The chip when mounted on the substrate is positioned over the top portion of the substrate and lowered thereon either by hand or with a mechanical chip carrying device. The bottom portion of the metalized via hole is indexed over a top of one end of a transmission line on the top portion of the substrate with the indexing tolerance between the two interfacing surfaces in a range of 0.5 to 10 mils.

Abstract: Semiconductor device contact pads are enhanced by forming a metal plate over at least a portion of the contact pad. "Enhancement" includes repair such as by bridging a reinforcing pad area over probe damage, general reinforcement or enlargement of a contact pad, and placement of a protective buffer pad over a contact pad. These methods are applicable to any semiconductor device with contact pads on a surface thereof, such as entire wafers, individual dice, and multi-chip High Density Interconnect (HDI) modules. The pad enhancement plate is formed by applying a planarizing dielectric layer over the entire device (if not already formed in the initial stages of HDI processing), and an enhancement access via is then formed to expose a portion of the contact pad to be enhanced. The entire device is metallized, and metal not over the exposed portion of the contact pad is subsequently removed.

Abstract: A fault tolerant communication arrangement, for switching parallel N-bit information among a plurality of stations, includes an M-bit crossbar switch, where M is greater than N by a number S of supernumerary or spare bit paths. At each station, an interface unit monitors for errors, and when an error is identified to a bit in the transmission path, routes the defective bit to one of the spare bit paths. All stations reroute data from the defective bit path to the same spare bit path. Error coding information is generated at the transmitting interface unit, and transmitted over some of the supernumerary bit paths, and when the number of defective bit paths reduces the number of available supernumerary bit paths to zero, the bit intensity of the error coding is reduced, to free additional supernumerary paths. In a system in which some of the stations include memory, a failure of a memory bit at a particular address is, in effect, a failure of that bit in an overall transmission path.

Abstract: Gunning mixes and other magnesia-based refractory compositions are disclosed which include up about to 10% by weight sulfamic acid as a binder. Sulfamic acid reacts readily with periclase grain and, when employed with boric acid and ceramic sintering aids forms an excellent binder system.

Abstract: A method of storing energy at ambient temperature and recovering same at an elevated temperature which comprises decomposition of a chemical compound at high temperature with a decomposition product being used to form another compound at low temperature. Upon regeneration of the decomposition product from the other compound there is a release of the originally absorbed high temperature thermal energy.

Abstract: A method of storing energy at ambient temperature and recovering same at an elevated temperature which comprises decomposition of a chemical compound at high temperature with a second compound being used to form another product at low temperature. Upon regeneration of the decomposition product from the first compound there is a release of the originally absorbed high temperature thermal energy.