Abstract: A method of making a semiconductor structure for use in a static induction transistor. Three layers of a SiC material are on a substrate with the top layer covered with a thick oxide. A mask having a plurality of strips is deposited on the top of the oxide to protect the area underneath it, and an etch removes the oxide, the third layer and a small amount of the second layer, leaving a plurality of pillars. An oxidation step grows an oxide skirt around the base of each pillar and consumes the edge portions of the third layer under the oxide to form a source. An ion implantation forms gate regions between the skirts. At the same time, a plurality of guard rings is formed. Removal of all oxide results in a semiconductor structure to which source, gate and drain connections may be made to form a static induction transistor. A greater separation between a source and gate is obtained by placing a spacer layer on the sidewalls of the pillars, either before or after formation of the skirt.

Abstract: A dual gate power switch comprised of a vertical arrangement of a normally off SIT (static induction transistor) in series with a normally on SIT in a monolithic semiconductor structure. The structure includes a first pillar having at the base thereof laterally extending shoulder portions having sections of a first gate for controlling the normally off SIT. The structure includes a second pillar, of a width greater than the first pillar and which also has laterally extending shoulder portions having sections of a second gate for controlling the normally on SIT. Contacts are provided for SIT operation.

Abstract: A technique for reducing power requirements in a communication transponder by converting signals in multiple uplink channels carried in frequency division multiplexed (FDM) form on multiple uplink beams, to a lesser number of downlink beams that operate in time division multiplexing (TDM) but at a bandwidth different from and preferably greater than the bandwidth of the uplink channels. Because the TDM downlinks can utilize amplifiers operating at or near peak power, whereas conventional FDM downlinks must operate with amplifiers backed off to minimize intermodulation products, use of the TDM downlinks effects significant power savings.

Abstract: A rudder control system having adjustable rudder drive turn off and “turn on,” and component wear monitoring. The rudder drive “turn off” being adjusted in accordance with the rudder stop position relative to the rudder order stop position, thereby improving position accuracy. Frequency of system “turn on” is compared to an acceptable “turn on” frequency for solenoid operation. Should the “turn on” frequency exceed the acceptable “turn on” frequency, the rudder angle at which “turn on” is implemented is adjusted to protect solenoids in the system from burnout. The rate of change of the rudder repeatback signal is monitored. A slow rate of change providing an indication of some component problem.

Abstract: Apparatus, methods, systems and devices for providing a temperature independent laser by determining a temperature dependence of a lasing wavelength, selecting the lasing wavelength having minimal temperature dependence and constraining the lasing wavelength of the laser device to the selected lasing wavelength. In an embodiment, a volumetric Bragg grating in photo-thermal refractive glass is used as a laser cavity mirror for constraining the laser emission at the selected wavelength. The laser device may be a broad spectrum laser such as an Er3+ doped glass broad spectrum laser. In an embodiment, the lasers are operated where the temperature dependence of the stimulated emission cross section is used to compensate for temperature dependent changes of other laser components.

Abstract: A digital automatic level control system employs delay elements, which enable information about a signal parameter from the past, present and future to be processed to provide an optimal gain that can be used to level rapidly varying signals, such as bursty signals. As digital time samples of a signal are passed through first and second buffers, first and second accumulators maintain running sums that are related to the sum of the samples presently in the first and second buffers, respectively. The sums in the first and second accumulators represent information about the signal parameter for the future and the past, respectively. By choosing the maximum of these two values, the system can anticipate the beginning of a signal burst, and still have enough delay to compensate the end of a signal burst. In one embodiment of the invention, multiple channel signals can be leveled, either individually or in groups.

Abstract: Signal conversion is implemented employing a memory system operating as a look-up table that stores a plurality of sets of output samples associated with each of a plurality of respective input samples. The look-up table thus can generate a corresponding set of output samples in response to a given input sample, thereby emulating desired digital upsampling and delta-sigma modulation. The output samples can be aggregated, such as by multiplexing, to provide an output data stream at a desired sample rate.

Abstract: A method of applying a moisture barrier seal to a fiber optic coil includes mounting a fiber optic coil in a vacuum deposition chamber, so as to expose a large exterior surface area of the fiber optic coil to an interior portion of the deposition chamber. The method further includes reducing the air pressure within the chamber to a value that is less than ambient pressure outside of the chamber. The method further includes introducing a vapor form of a non-porous material, preferably parylene, into the chamber. The vapor form of the non-porous material changes into a solid state upon contact with the fiber optic coil, so as to form a conformal coat on the fiber optic coil.

Abstract: A hybrid laser source including a solid state laser driven by an array of fiber laser amplifiers, the inputs of which are controllable in phase and polarization, to compensate for distortions that arise in the solid state laser, or to achieve desired output beam properties relating to direction or focus. The output beam is sampled and compared with a reference beam to obtain phase and polarization difference signals across the output beam cross section, at spatial positions corresponding with the positions of the fiber laser amplifiers providing input to the solid state laser. Therefore, phase and polarization properties of the output beam may be independently controlled by predistortion of these properties in the fiber laser amplifier inputs.

Abstract: Formation of a regrowth layer of a Group III–V semiconductor material is facilitated by prior formation of an intermediate layer, selected primarily for its smooth morphology properties. The intermediate layer is formed over an underlying substrate and over a dielectric layer formed over portions of the substrate. The intermediate layer maintains the monocrystalline properties of the underlying substrate in regions other than those covered by the dielectric layer, and improves the electrical and morphology properties of the regrowth layer formed over the intermediate layer.

Abstract: An integrated switched filterbank and method of forming an integrated switched filterbank is disclosed. One embodiment includes a switched filterbank that includes an active subassembly, a plurality of active devices mounted to the active subassembly, and a stripline filter subassembly stacked below the active subassembly. The stripline filter subassembly includes a plurality of stripline filters of varying passbands embedded therein, wherein the plurality of stripline filters are coupled to active devices mounted on the active subassembly through a set of contacts extending from the stripline filters through the active subassembly to at least one of the plurality of active devices.

Abstract: The present invention provides strategies for detecting intrusions in wireless environments, and the strategies are based on innovative applications of information analysis as well as other information correlating techniques. The key to detecting intrusions in a RF based environment is to understand the normal spectrum of behavior so that deviations can be detected and analyzed. For a wireless communications grid, this process requires empirical knowledge about how the radios work together as components of the information grid, and how this grid network is managed. Once normal behavior has been characterized, anomalous behavior can be identified. Potential intrusions into the wireless network can be analyzed and an attack model can be created. The attack model can be utilized as the basis for initiating appropriate adaptive responses.

Abstract: A double heterojunction bipolar transistor structure having desirable properties of a low base-emitter turn-on voltage and no electron blocking discontinuities in the base-collector junction. These properties are achieved by selecting base, emitter and collector materials to provide a bandgap profile that exhibits abrupt transitions at the heterojunctions, such that both abrupt transitions are due to transitions in the valence band edge of the bandgap, but not in the conductive band edge of the bandgap.

Abstract: An apparatus in one example comprises a wafer portion that comprises a conduction layer. Upon exposure of the conduction layer during a etch of the wafer portion, the conduction layer serves to dissipate a portion of a charge buildup on the wafer portion during an etch of the wafer portion.

Abstract: A communications system (10) which utilizes an M-ary QAM signal constellation suitable for non-linear applications. The communications system includes a modulator (18) for utilizing the M-ary constellation to implement the modulation. The M-ary constellation is a circular constellation which provides a simplified amplitude predistortion by utilizing the subject M-ary constellations, enabling more efficient communications can then be achieved through a peak-power-limited non-linear channel (16). Such non-linear channels (16) are more power efficient at creating RF energy from DC energy.

Abstract: A high resolution pen-sized projector for controlling the position and size of an image generated by a closed loop control system consists of four major system components including: a virtual VGA display located inside of a XGA display, a position acquisition system, a displacement compensating control system to determine correct position of the VGA display inside of the XGA display, and a dark display area of the background portion of the XGA display.

Abstract: A coupled cavity circuit for a microwave electron tube comprises at least two resonant cavities adjacent to each other. An electron beam tunnel passes through the coupled cavity circuit to allow a beam of electrons to pass through and interact with the electromagnetic energy in the cavities. An iris connecting the adjacent cavities allows electromagnetic energy to flow from one cavity to the next. The iris is shaped to cause the iris mode passband to be lower in frequency than the cavity mode passband while still providing broadband frequency response. In addition, the present coupled cavity circuit operates on an electron beam to interact with the third space harmonic of the second passband (the cavity passband) of the electromagnetic signal. Preferably, this interaction occurs on the second passband as this operational design provides output with higher frequencies without decreasing the cavity size. Furthermore, this operational design provides more frequencies with no increase to the iris size.

Abstract: A protective structure for thermal insulation and impact resistance, and especially suited for bonded application to the exterior of aircraft including spacecraft to protect the craft from high temperatures generated by exhaust gases and by atmospheric re-entry. The structure includes either a single ceramic tile component with a cover component comprising a fiber reinforced ceramic matrix composite encasing the tile component, or a plurality of ceramic tile components with a like single cover component encasing the plurality of tile components. Utilizing the structures as an external aircraft surface imparts a super hard exterior that functions to significantly prohibit impact and erosion damage while not compromising the desirable thermal insulation properties inherent to tile.

Abstract: A linear beam device comprises a cathode and an anode spaced therefrom, with the anode and cathode being operable to form and accelerate an electron beam. An RF interaction region having a drift tube is arranged relative to the anode to permit the electron beam to pass therethrough. A multi-stage depressed collector of the linear beam device has a plurality of collector electrodes successively arranged to collect spent electrons of the electron beam after passing through the RF interaction region. Each one of the plurality of collector electrodes has a distinct voltage level applied thereto defining a decelerating electric field within the collector. At least one of the plurality of collector electrodes further comprises a collecting surface having a shape that is normal to a coincident trajectory of the spent electrons, whereby a substantial portion of the collecting surface is covered with a plurality of narrow grooves.

Abstract: A semiconductor cooling arrangement wherein a semiconductor is affixed to a thermally and electrically conducting carrier such as by brazing. The coefficient of thermal expansion of the semiconductor and carrier are closely matched to one another so that during operation they will not be overstressed mechanically due to thermal cycling. Electrical connection is made to the semiconductor and carrier, and a porous metal heat exchanger is thermally connected to the carrier. The heat exchanger is positioned within an electrically insulating cooling assembly having cooling oil flowing therethrough. The arrangement is particularly well adapted for the cooling of high power switching elements in a power bridge.