Abstract: A plurality of end caps engagable with a microwave cavity each have an underside configured differently to cause the microwave cavity to have different electrical responses depending on which end cap engages the microwave cavity. A microwave device includes a cylindrical cavity and an end cap movable within the cavity to change its axial position within the cavity thereby varying the volume and the electrical response of the cavity.

Abstract: A method is provided for using a lunar flyby maneuver to transfer a satellite from a quasi-geosynchronous transfer orbit having a high inclination to a final geosynchronous orbit having a low inclination. The invention may be used to take the inclination of a final geosynchronous orbit of a satellite to zero, resulting in a geostationary orbit, provided that the satellite is launched in March or September.

Abstract: A transverse-electric waveguide filter is provided for transmitting a fundamental transverse-electric mode in a first frequency band while attenuating an associated higher-order transverse-electric mode in a second frequency band. The filter includes transverse corrugations between input and output waveguide ports to attenuate the higher-order transverse-electric mode. The input and output waveguide ports have a characteristic impedance and the filter also incudes a ridge system that is coupled between the first and second waveguide ports and is configured to provide a signal-path impedance that substantially matches the characteristic impedance to thereby support transmission of the fundamental transverse-electric mode from the input port to the output port.

Abstract: A waveguide switch matrix is disclosed. The switch matrix includes a number of input waveguides that may be selectably connected to a number of output waveguides. A switch apparatus is provided at the intersection of each input waveguide and each output waveguide. The switch apparatus includes probes inserted into both the input waveguide and the output waveguide. The probes are connected through a switch arrangement. When a particular input waveguide is to be coupled to a particular output waveguide, the switch arrangement between the probes of the waveguides is closed to provide a signal path for the electromagnetic energy.

Abstract: A power divider/combiner for dividing received powers at 4 input ports, transmitting the divided powers to each of 4 output ports and combining the transmitted powers at each of the output ports. The power divider combiner has through transmission lines flanked on either side by secondary through transmission lines that interconnect corresponding input and output ports. The through transmission lines are likewise interconnected at a center node by a plurality of branch transmission lines. A method for making a power divider/combiner includes merging two 0 dB couplers by joining the center points of each of the branch transmission lines.

Abstract: A method and system (10) for simultaneous operation of primary (14A-14D) and redundant (16A-16D) motor windings in a redundant stepper motor (12). The redundant motor system (10) has a control circuit (11) including a phase synchronizer (36) for establishing a relationship between predetermined primary and redundant motor windings (14A-14D and 16A-16D) such that the power consumption is increased and the motor torque is affected. In one embodiment of the present invention the predetermined motor windings (14A-14D and 16A-16D) are operated in phase thereby doubling the power consumption and increasing the torque. In another embodiment, the predetermined motor windings (14A-14D and 16A-16D) are operated in phase quadrature thereby doubling the power consumption and increasing the torque by less than 50%. In yet another embodiment, the predetermined motor windings (14A-14D and 16A-16D) are operated out of phase with each other thereby doubling power consumption and producing zero torque.

Abstract: An apparatus for storing energy and actuating the attitude of a spacecraft includes a first gimbaled flywheel assembly having a first rotor rotating in a first direction, and a second gimbaled flywheel assembly having a second rotor rotating in a second direction opposing the first direction. The first and second gimbaled flywheel assemblies are adapted to store and release energy and to actuate the attitude of the spacecraft. The apparatus includes one or more non-gimbaled counter-rotating flywheel pairs that are adapted to store and release energy.

Abstract: The present invention provides a method of performing statistical classification that can resolve conflict in independent sources of information, thereby creating a robust statistical classifier that has superior performance to classifiers currently available. Additionally, the present invention is automatically trainable, yielding improved classification performance. The present invention may be embodied in a method of statistically classifying events or objects, including the steps of gathering sets of information representative of features of an object or event; creating basic probability assignments based on said sets of information; determining a coarse information set from said sets of information; performing coarsening on said sets of information; performing linear superposition on each feature; and combining all features to reach a conclusion.

Abstract: A launch quasi-optical amplifier including a photonic bandgap crystal, designed to operate within a specific frequency range. The photonic bandgap crystal is populated with active devices that are coupled to the alternate layers, or defects, in the crystal to compensate for the absorption in the alternate layers thereby creating a negative absorption coefficient. The photonic bandgap crystal is operable as an amplifier when the active devices are amplifiers, and as a wave source when the active devices are oscillators.

Abstract: A method and apparatus for estimating attitude sensor bias in a satellite system uses attitude sensors and a spacecraft control processor. Attitude sensors provide output signals, which may contain bias. The present invention interprets the signals, determines the bias present in the signals, and generates an output signal to offset the bias in the signals from the attitude sensors, thereby leading to more accurate positioning of the satellite employing the present invention.

Abstract: A method and apparatus for autonomous acquisition of attitude in a stellar inertial spacecraft attitude system is disclosed. The present invention uses star trackers, an on-board star catalog, spacecraft steering and inertial sensors to determine spacecraft attitude. The present invention utilizes pattern match and pattern rejection methods and uses multiple stellar snap-shots in conjunction with spacecraft steering and spacecraft inertial measurements to acquire spacecraft attitude. Spacecraft inertial measurements are used to connect multiple stellar snap-shots to provide adequate star information that can be used to acquire spacecraft attitude. In an attitude determination system using star trackers, the star trackers may have a narrow field-of-view or few stars may be available for viewing. The present invention uses pattern matching and pattern rejection on different sets of stars, thereby allowing attitude acquisition when the number of stars in view is small.

Abstract: A system for distributing first and second television signals of diverse modulation formats to a number of locations in a multiple-dwelling unit includes first and second antennas for receiving, at the multiple-dwelling unit, respective first and second received television signals having respective first and second, different modulation formats. The system also includes first and second transmodulators for transmodulating the first and second received television signals, respectively, to develop first and second transmodulated signals, respectively. A combiner or diplexer combines the first and second transmodulated signals into a combined signal, and a distributing network distributes the combined signal to each of a plurality of locations. A diplexer at a particular location selected from the number of locations separates the combined signal to recover the first and second transmodulated signals.

Abstract: A capacitive coupler for a microwave circuit that has a first cavity and a second cavity separated by a wall. The separating wall has an aperture that, due to its shape, is capacitive. The aperture has a pair of elongated walls separated by a pair of side walls. The elongated walls and the side walls each have a thickness substantially thicker than what is now the industry standard. At least one of the elongated walls has a ridge. Because the distance between the first elongated wall and the second elongated wall is substantially greater than that previously known, the aperture may be easily manufactured.

Abstract: A spacecraft control system having a spacecraft with a gimbaled thruster attached thereto. An actuator is operationally attached to the gimbaled thruster to control the angled position of the gimbaled thruster in two orthogonal directions. A position control system is provided which sends a control signal to the actuator which moves the gimbaled thruster to an angled position in response to the control signal, wherein the angled position of the gimbaled thruster controls the attitude and orbital velocity of the spacecraft.

Abstract: A low profile, low cost receiver/transmitter system includes a planar waveguide-to-microstrip adapter, a dielectric loaded waveguide fed slot array antenna, and a downconverter all formed on a single dielectric substrate made of polytetrafluoroethylene. The waveguide antenna includes a set of slots disposed in a surface thereof to receive/transmit a microwave/millimeter wave signal. The waveguide-to-stripline adapter is connected to the waveguide antenna and includes a taper section attached to a microstrip line. The taper section, which may be linear or may follow some other more complex taper function such as a Chebyshev function, adapts a signal propagating within the waveguide antenna to the microstrip line or vise versa.

Abstract: A process is provided for fabricating MODFET's in group III nitride compound semiconductors. The process precedes isolation of the MODFET structure with the use of e-beam lithography to define very narrow (e.g., .about.0.25 micrometer) gates which enhance transistor microwave cut-off frequency. Because these compound semiconductors resist chemical etchants, isolation is accomplished by etching with reactive ions to form an isolation mesa having a vertical mesa sidewall. To improve breakdown, the mesa sidewall is covered with a passivation layer prior to deposition of a gate feed that contacts the gate. To reduce parasitic gate capacitance, the gate feed is spaced from a narrow edge of the transistor's two-dimensional electron gas.

Abstract: A paint is a liquid or solid mixture of a plurality of particles and an inorganic binder such as a silicate. The particles have a composition A[xAl(1-x)Ga].sub.2 O.sub.4.+-..gamma. (.delta.In), wherein A is zinc, magnesium and/or cadmium, the value of x is from 0 to 1, the value of .delta. is from 0 to about 0.2, and the value of .gamma. is less than about 0.2. In the liquid mixture, a paint vehicle is also typically present to impart the desired fluidity to the mixture. The solid paint made using this material is white, has very low solar absorptance, and may be made electrically conductive by doping the particles with indium or other appropriate dopant.

Abstract: A dual band omni directional antenna is disclosed. A dielectric cylinder supports a cone shaped reflector over a corrugated radio frequency horn. Orthogonal mode transducers produce and conduct circularly polarized radio frequency waves within the horn. The reflector, the horn, and the transducers are all coaxially disposed. The antenna produces a torodial radiation pattern in a plane that is substantially orthogonal to the axis of the antenna. Transmit and receive functions may be performed simultaneously using a single reflector and two orthogonal mode transducers.

Abstract: Spacecraft maneuvers (e.g., orbit transferring, stationkeeping and attitude controlling) of a first spacecraft are realized with conventional force and torque generators (e.g., thrusters and momentum wheels). Spacecraft maneuvers of a second spacecraft are realized through magnetic interaction between the first and second spacecraft. In particular, a magnetic moment vector m.sub.1 of a magnetic system of the first spacecraft and a magnetic moment vector m.sub.2 of a magnetic system of the second spacecraft are adjusted to apply selected force vectors and torque vectors to the first and second spacecraft.

Abstract: A structure includes an electronic device support, an electronic device, and a fastener for the electronic device support and the electronic device. There is a first dovetail slot in the electronic device support and a second dovetail slot in the electronic device. The first dovetail slot and the second dovetail slot are in a facing relationship. A bar of a shape-memory alloy in the recovered state is received into the first slot and the second slot and has a cross sectional shape with V-shaped grooves on its opposing lateral sides engaging the first dovetail slot and the second dovetail slot.