Abstract: Providing a tapered surface reflectivity to the reflecting surface of the parabolic reflector in a parabolic antenna using resistive material reduces side lobes and produces steeper roll off in the principal lobe, permitting use in the antenna of a smaller diameter microwave feed than required by an antenna without that tapered surface resistivity and, effectively, emulates the latter antenna. As a consequence of the smaller feed diameter, multiple feeds may be positioned contiguously to form multi-beam antennas that produce contiguous beam patterns. A satellite cellular communications multi-beam antenna incorporating the invention achieves greater regional coverage of the Earth.

Abstract: An antenna system comprising a feed array, a subreflector and a main reflector which are oriented to define a front-fed dual reflector antenna geometry. The feed array is comprised of a plurality of separate feeds which are aligned in a predetermined contour. Each feed array is coupled to a feed network which acts to combine the illumination beams of clusters of a preselected number of feeds to produce a plurality of composite illumination beams. Each composite illumination beam is directed to be incident upon a separate predetermined location on the subreflector which directs the composite illumination beams towards the main reflector. Each composite illumination beam is reflected by the main reflector in a preselected direction so that each composite illumination beam forms an antenna beam that impinges a predetermined coverage area on the Earth.

Abstract: A vehicle launch system having an acoustic insulator, wherein the acoustic insulator is an inflatable assembly disposed between a shroud and a spacecraft vehicle and containing gaseous material for dampening the acoustic noise effect in a spacecraft vehicle ferrying cavity during the initial vehicle launch stages.

Abstract: A relatively low voltage, high speed, differential diode transistor logic DDTL) family of circuits for performing various Boolean logic functions, such as AND, OR, etc. as well as non-Boolean functions, such as buffering and storage. The logic family may be configured in emitter coupled logic (ECL), also known as current mode logic (CML), with bipolar transistors, such as bipolar junction transistors (BJT) or heterojunction bipolar transistors (HBT). The logic family can also be implemented in source-coupled field effect transistor logic (SCFL) and utilize FETs, MOSFETs, HEMTs and MESFETs. In accordance with one aspect of the invention, gate circuits configured for reduced voltage multiple input operation only include input diodes connected to one of the transistors forming the differential pair, thus reducing the number of input diodes by one half.

Abstract: Method and apparatus for complex phase equalization in a communication system. The method includes receiving and downconverting a two-dimensional communication signal to generate in-phase (I) and quadrature (Q) components that have been phase-rotated by an unknown amount during propagation from a transmitter, and then processing the I and Q signals in a cumulant recovery processing system to obtain phase correction of the I and Q signals prior to demodulation. The final step is demodulating the two-dimensional communication signal. Phase correction is effected without regard to modulation type and independently of the demodulating step.

Abstract: A polarized planar log periodic antenna is described that is simple in structure and compact in form and which in the dual circularly polarized form may serve as a direct replacement for less capable antennas in RF systems, such as countermeasures systems. An embodiment is characterized by a pair of relatively flat planar linear polarized log periodic antennas of the kind including a plurality of metal radiating elements, each of said radiating elements having the geometry of a circular arc; and the pair of antennas are attached in common to a planar dielectric base; one of said antennas being angularly oriented by ninety degrees relative to the other of said antennas with the radiating elements of one antenna interleaved with the corresponding radiating elements of the other antenna without direct electrical contact between the two antennas. Variations of the structure and novel RF feed line assembly are also described.

Abstract: A system and corresponding method of its operation, for configuring a communication network of multiple interconnected computers. The system includes a graphical user interface (36) that facilitates the functions of task organization development (38), platform equipment development (40), address book development (60) and logical network development (42) in a simulated planning phase of operation (30). Using the system, an authorized user performs these development functions to define one or more logical communication networks, and then the system automatically generates specifications for a corresponding physical communication network (44), including management information blocks (74). In a dissemination phase of operation (32), the management information blocks are transmitted (50) to the network computers.

Abstract: A passive millimeter-wave imaging system (10) that includes a millimeter-wave camera (12) positioned at the end of an aircraft landing strip (14) to provide an image (20) of the aircraft (16) approaching the landing strip (14) along a landing glidepath (18). The camera (12) broadcasts the image (20) of the aircraft (16) approaching the landing strip (14) to the aircraft (16) and to a control tower (24). With this information, the pilot of the aircraft (16) sees his aircraft's position relative to the glidepath (18), and can make landing adjustments accordingly. Likewise, the tower personnel can monitor the aircraft landing glidepath (18) to insure that the aircraft (16) maintain a safe distance relative to the ground.

Abstract: An antenna system comprising a feed array, a subreflector and a main reflector which are oriented to define a side-fed dual reflector antenna geometry. The feed array is comprised of a plurality of separate feeds which are aligned on a predetermined contour. Each feed array is coupled to a feed network which acts to combine the illumination beams of clusters of a preselected number of feeds to produce a plurality of composite illumination beams. Each composite illumination beam is directed to be incident upon a separate preselected location on the subreflector which directs the composite illumination beams towards the main reflector. Each composite illumination beam is reflected by the main reflector in a preselected direction so that each composite illumination beam forms an antenna beam that impinges a predetermined coverage area on the Earth.

Abstract: The present invention provides a capacitive resolver (100). The capacitive resolver (100) includes a charge plate (102), a sensing plate (106), and an interrupter plate (400) positioned between the charge plate (102) and the sensing plate (106). The front surface of the sensing plate (500) has a sinusoidal pattern (502). The back surface of the sensing plate (600) includes charge detectors (602), charge collectors (608), and rectifiers (618). The capacitive resolver (100) also includes a signal generator (110) which is electrically connected to the charge plate (102) and a signal analyzer which is electrically connected to the sensing plate (106). The capacitive resolver (100) may additionally include a non-conductive support (112).

Abstract: A system and method for implementing the paging and protection attributes, such as block protection and access lock and key functions promulgated in MIL-STD-1750A. The present invention takes advantage of the PowerPC microprocessor architecture to implement the paging and protection attributes required by MIL-STD-1750A in hardware. Since the paging and the protection attributes are implemented in hardware, the system performance is greatly improved.

Abstract: A horn antenna is provided which is capable of operating at a plurality of separate frequencies while providing substantially equalized E and H-plane patterns for each of the separate frequencies. The antenna includes a coupling portion to permit coupling to a communication device. An inner portion is coupled to the coupling portion, and includes a first choke having a depth which extends substantially parallel to a central longitudinal axis of the antenna and a width which extends in a radial direction of the antenna. The depth and the width of the first choke are set so that the first choke will operate at the first frequency. An outer portion is coupled to the inner portion, wherein the outer portion has a maximum diameter in the radial direction which is greater than the maximum diameter in the radial direction of the inner portion.

Abstract: An antenna feed horn (10) for a satellite antenna array that includes multiple chokes (34, 36, 40, 42, 44) that provide effective control of the horn aperture mode content to generate radiation patterns which substantially have equal E-plane and H-plane beamwidths, low cross-polarization, low axial ratio, and suppressed sidelobes. The chokes (34, 36, 40, 42, 44) are annular notches that have both radial and axial dimensions. Two chokes (34, 36) are provided at an internal transition location between a conical profile section (14) and a cylindrical aperture section (16). Additionally, another choke (44) is provided in the aperture (20) of the horn (10), and two additional chokes (40, 42) are provided proximate the aperture (20).

Abstract: A diode array (32) which includes a diode bar (22) having a plurality of laser diodes (42) within an active region (40) so as to emit light parallel to an optical axis (26), generally parallel to the laser diodes (42). The diode bars (22) are sandwiched between a pair of spacer layers (34, 36). Each spacer layer (34, 36) includes two or more spacers (48, 50). The spacers (48, 50) in each layer (34, 36) are configured such that gaps (52, 54) between contiguous spacers (48, 50) are at a non-parallel angle (&THgr;) relative to the optical axis (26) of the diode bar (22). By orienting the gaps (52, 54) between the spacers (48, 50) at non-parallel angle relative to the optical axis (26) of the laser diodes (40), the gaps (52, 54) span several laser diodes (40), thus averaging any inhomogeneous effects caused by the gaps (52, 54) resulting in a relatively more uniform output from the various laser diodes (40) forming the diode bar (22).

Abstract: A method for processing received radio signals that are subject to unwanted change during propagation through the atmosphere, from a transmitter to a receiver array. The multiple signals are received as cochannel signals at the antenna array, and are processed to eliminate the effects of modification of the signals during propagation, wherein the processing step includes cumulant-based signal recovery without regard for the geometrical properties of the antenna array. In the invention as disclosed, two different information signals having two different polarization states are transmitted, and at least one of the transmitted signals is subjected to an unwanted change of its polarization state. The received signals are processed to separate and recover the two information signals without regard to their polarization states.

Abstract: A Bragg grating device (10) is provided including a semiconductive optical waveguide (12) with a Bragg grating structure (14) formed along its length. A first plurality of electrodes (16) are disposed on a first surface (18) of the optical waveguide (12) and individually communicate with select members of the Bragg grating structure (14). A second plurality of electrodes (20) are disposed on a second surface (22) of the optical waveguide (12) and individually communicate with select members of the Bragg grating structure (14) such that individual electrodes of the second plurality of electrodes (20) are electrically coupled to individual electrodes of the first plurality of electrodes (16) via the Bragg grating structure (14). As such, a plurality of addressable portions (30) of the Bragg grating device (6) are defined.

Abstract: A passive millimeter-wave imaging system (10) is disclosed that provides a full 360° instantaneous azimuthal field-of-view (54) image of a scene. The imaging system (10) makes use of a spherical Luneburg lens (12) and a series of millimeter-wave direct detection receivers (24) configured in a ring (16) around the lens (12), and positioned at the focal plane of the lens (12). The series of receivers (24) are positioned on a plurality of consecutive sensor cards (14), where each card (14) includes a certain number of the receivers (24). The receivers (24) define a one-dimensional focal plane array with limited obscuration, and thus give a 360° instantaneous field-of-view (54) of a slice of the scene. Processing circuitry (32), including a multiplexing array interface for multiplexing the signals from the receivers (24), are positioned on an outer ring (34) outside of the sensor card ring (16).

Abstract: An angle cavity resonant photodetector assembly (8), which uses multiple reflections of light within a photodetector (14) to convert input light into an electrical signal. The photodetector (14) has a combination of generally planar semiconductor layers including semiconductor active layers (20) where light is converted into an electrical output. The photodetector (14) is positioned relative to a waveguide (10), where the waveguide (10) has a waveguide active layer (22) located between a pair of waveguide cladding layers (24) and (26) and includes a first end (28) for receiving light and a second end (30) for transmitting the light to the photodetector (14). The photodetector (14) has a first reflector (12) and second reflector (16) that provides for multiple reflections across the semiconductor active layers (20).

Abstract: An RF cable contains an coaxial inner conductor and a coaxial outer shield surrounding the inner conductor in a concentric arrangement. Quarter-wave series sections in the inner conductor and the outer shield severs a direct thermal path along the RF cable, providing low thermal loading for a cryogenic-to-ambient temperature interconnection. The resonant structure of the RF cable permits propagation alternating current and blocks direct current. A method of forming the RF cable comprises depositing metal on a substrate composed of a polymer film having very low thermal conductivity, and winding the metallized substrate into a tubular configuration. The inner conductor may extend laterally beyond the outer shield to provide points of electrical contact.

Abstract: A vacuum chuck (34) for holding thin sheet material, particularly during high-temperature manufacturing processes, and an apparatus (10) for forming a substantially uniform coating of a substance on a thin sheet material. The vacuum chuck includes a chuck body (36) having a gas-permeable support surface (38) for supporting the thin sheet material to define a vacuum chamber (49) having an inlet (54), a valve member (56) for controlling fluid flow through the vacuum chamber inlet, and a locking shim (58) for holding the valve member in the vacuum chamber inlet.