Abstract: A dual-band patch antenna element (10) for circular or linear polarization. The patch element (10) is excited by two different hybrids (22, 24), designed for transmit and receive bands respectively. Each hybrid (22, 24) electromagnetically couples a pair of orthogonal ground plane slots (26, 28, 30, 32) that excite the patch antenna (10). The hybrid (22) and slot (26, 28) dimensions for the transmit band are different from the hybrid (24) and slot (30, 32) dimensions for the receive band. Isolation can be improved by connecting shunt stubs (34, 36) to the hybrids (22, 24).

Abstract: A system and method for adjusting satellite communication signal transmit power for signals transmitted to a localized region within a satellite coverage area utilize real-time information on weather conditions (172) and/or actual path losses (174) within the localized regions to adjust the effective isotropic radiated power (EIRP) of the satellite beams (188) to minimize the total radio frequency (RF) power required for transmission. The transmission system may be realized using a variety of antenna types for transmitting spot beams and/or area coverage beams. Representative antenna implementations include multi-beam antennas having a low-level beamforming network and hybrid matrix amplifier system, phased-array with independent input amplitude control and beamsteering for each beam, and a phased-array feeding a confocal imaging system for single broadcast beam per polarization.

Abstract: An electrochemical cell has electrode leads of different lengths extending from the terminals to the respective plate sets of the cell. The electrode leads have a cross-sectional area which varies along the length of the electrode leads, such that the electrical resistances of the electrode leads are substantially the same. Typically, each electrode lead has a first region having a first cross-sectional area, and a second region having a second cross-sectional area. The relative lengths of the first region and the second region of the electrode leads are varied to achieve the substantially constant total resistance.

Abstract: A microwave stripline signal distribution system utilizes a central conductor that is supported on a substrate, which is itself captured and supported between two foam layers. External ground plane shielding is provided on each side of the foam/central-conductor-substrate sandwich. The metallic central conductor is thin, as are the other structural elements, leading to a lightweight signal distribution system. The central conductor may be patterned to provide a large number of feeds. The approach allows: the inexpensive fabrication of lightweight signal distribution boards, whose inputs and outputs may be combined to provide single-channel or multi-channel combination or division of microwave signals. In a typical application, there is combination or division of microwave signals in an antenna involving hundreds of individual feed horns.

Abstract: A semiconductor device includes a substrate such as indium phosphide having a trap density which increases with increasing distance from a top surface of the substrate, so that the electrical conductivity of the substrate increases with increasing distance from the top surface. An active device structure is built on the substrate and is disposed adjacent to the top surface of the substrate. A biasing structure has a buried electrode disposed below the top surface of the substrate a distance of from about 0.1 to about 2 micrometers, and an electrical contact at a surface of the substrate and in electrical communication with the buried electrode. A biasing source applies a biasing voltage of from about 0.2 volts to about 5 volts to the electrical contact. The biased subsurface contact protects the active device structure from current induced in the substrate by energetic particles and other radiation.

Abstract: A spacecraft protected by a coating includes a spacecraft such as a communications satellite has an external surface and a coating on the external surface of the spacecraft. The coating is formed of a binder, and a plurality of pyroelectric/ferroelectric pigment particles, preferably ferroelectric particles, bound together by the binder. Each ferroelectric pigment particle includes a ferroelectric pigment material having a ferroelectric/paraelectric transition. The coating may also include active secondary particles and/or inert particles. The coating may operate in a passive mode or an active mode with the application of a bias voltage to the coating.

Abstract: An analog-to-digital converter is used to convert a known analog signal to a digital output. The output is then compared to a known digital output that corresponds to the known analog signal. If the two do not match, then the gain and frequency response of the analog-to-digital converter is tuned using a varactor control circuit until the digital output is correct.

Abstract: A satellite antenna pointing system has a reflector antenna for receiving an uplink signal from an earth based ground station and a satellite based phased array assembly for transmitting a downlink signal. Because extraterrestrial communications suffer significant losses during transmission, accurate pointing of both uplink and downlink antennas is desired in order to reduce required signal strength. The present invention uses two different methods for pointing the uplink and downlink antennas.

Abstract: A multi-step circular horn system may have several steps and may use more than one flared section based upon design considerations. In order to achieve high aperture efficiency, the aperture field distribution is close to uniform. For good cross-polar performance, the field distribution is circularly symmetric. Location and shape of the steps is determined by the wavelength of the signal being transmitted and the space constraints imposed by the antenna design. The step discontinuities generate desired modes of operation in the right proportion.

Abstract: Methods and systems for stabilizing satellite spin about an intermediate inertia axis (Z) are disclosed. A set of gyros (22) sense the X component and the Y component of the angular velocity of the satellite body. A single degree of freedom momentum wheel (26) has a fixed transverse orientation with respect to the intermediate axis in order to store momentum. In one embodiment, the momentum wheel (26) is oriented to store momentum parallel to the Y axis. A tachometer (30) senses the rotation rate of the momentum wheel (26). A processor (24) forms a control signal representative of a control torque to be applied to the momentum wheel (26). The control torque is based upon the X component and the Y component of angular velocity of the satellite, and the angular velocity of the momentum wheel (26).

Abstract: Apparatuses, methods and systems for mesh integration and tension control, mesh retention, and mesh management of mesh-type deployable reflectors. The mesh members are comprised of a plurality of wedge-shaped gore members, each of which are pre-tensioned initially utilizing double-sided tape in a temporary manner prior to final stitching. String-like chord catenary members are positioned in pockets formed on the outer end of the gore members. The mesh member is attached to a ribbed reflector frame structure through a plurality of nodal assembly mechanisms. The nodal assemblies have spring biasing members for tensioning radial and transverse chord members along the reflector surface. A plurality of string-like members positioned in washers on the mesh member are used to maintain a tension field in the mesh member when the reflector is in its collapsed and stowed condition.

Abstract: A video telemetry system for monitoring the deployment of an apparatus coupled to a satellite body includes a camera that produces a video signal. A video compressor is coupled to the camera and digitally compresses the video signal into a digitally compressed video signal. A modulator is coupled to the compressor for modulating the compressed video signal. An antenna is coupled to the modulator for converting the compressed video signal into an RF video signal and transmitting the RF video signal to a ground station or other means for monitoring the signal, particularly during a deployment.

Abstract: A satellite signal routing system includes a satellite using one or more waveguide switches for routing M-inputs to M of N-outputs. A waveguide switch includes a first waveguide, used as a stationary input coupled to a rotary joint. A joint rotation device, such as a motor, rotates the rotary joint. A rotary waveguide is attached to the rotary joint and also rotates. Two or more second waveguides, used as stationary outputs, are coupled to the rotary waveguide through a non-contacting waveguide. A controller controls the joint rotation device to rotate the rotary joint to align the rotary waveguide with one of the second waveguides.

Abstract: A system (10) and method (100) for charge and discharge equalization of a lithium-ion battery having a plurality of cells (12) in series. A central charge controller (16) and a central discharge controller (22) command a rate of charge to individual charge controllers (14) associated with each cell (12) of the battery for maintaining equalized charge at each cell (12) of the battery. The charging and discharging is initiated upon sensing a predetermined maximum charge threshold voltage (104) and a predetermined minimum discharge threshold voltage (114) at each cell in the series of cells.

Abstract: A tunnel diode has a quantum well having at least one layer of semiconductor material. The tunnel diode also has a pair of injection layers on either side of the quantum well. The injection layers comprise a collector layer and an emitter layer. A barrier layer is positioned between each of the injection layers and the quantum well. The quantum well has an epitaxial relationship with the emitter layer. An amount of one element of the well layer is increased to increase the lattice constant a predetermined amount. The lattice constant may have a reduction in the conduction band energy. A second element is added to the well layer to increase the conduction band energy but not to change the lattice constant. By controlling the composition in this matter, the negative resistance, and thus the effective mass, may be controlled for various diode constructions.

Abstract: A waveguide continuously variable power divider/combiner that is capable of dividing one input signal into two output signals, with the ratio of the output signals being continuously variable between zero and infinity. The waveguide has a first septum polarizer separated from a second septum polarizer by a ferrite phase shifter. By adjusting the magnetic bias in the ferrite phase shifter, a predetermined phase differential is generated thereby modifying an input signal as desired.

Abstract: A soft decision decodable short binary block coding arrangement is provided for use as an inner code with a Reed-Solomon outer code in a concatenated coding scheme. The inner code is a (n,k) short block code having a message length k×i, where i is a small integer selected to eliminate any need for interleaving between the inner and outer codes. Eliminating interleaving mitigates inner code decoder burst errors. The inner code is preferably formed as a punctured (15,11) Hamming code modified to form a (12,8) code sequence.

Abstract: A unique transistor model and methods for analyzing the model are disclosed. The transistor model of the present invention is simple and requires specification of a minimal number of parameters to simulate transistor operation. Three analysis methods are disclosed, each having unique circumstances for application A first method is premised on sampling all waveforms in the circuit and determining the operating point of the transistor. The first method assumes an input of an arbitrary periodic waveform. The first method is very flexible and may be used with a wide range of models other than the disclosed model. A second and a third method are premised on input and output waveform clipping. The second method assumes a single tone input into the transistor. The third method is a combination of features from the first and second methods. The third method is computationally efficient and assumes an arbitrary periodic input waveform.

Abstract: A system and method for charging a lithium-ion battery in which the battery is charged by a bulk charger at a high rate until one or more of the cells reaches a predetermined series threshold voltage. When a predetermined cell threshold voltage is reached, the controller provides instructions as to whether to reduce or terminate the cell charging by the bulk charger. At this point in time, the redundant power supplies begin charging each cell individually through balancing switches. The balancing switches will turn off as their respective cells reach a predetermined cell threshold voltage. Ultimately, each cell will be fully charged to an identical high charge state.

Abstract: A starter circuit particularly suitable for a plasma of an ion engine for a spacecraft includes a power supply having an output inductor with a tap. A switch is coupled to the tap. The switch has a control input. A pulse control logic circuit is coupled to said control input, said pulse control logic circuit controlling said switch to an off state to generate a high voltage discharge.