Abstract: A wireless communication platform utilizes flexible bandwidth assignment to re-allocate bandwidth between spot beams. The platform may assign a first combination of frequency and polarization (FP) to a first spot beam and a second combination of frequency and polarization to a second spot beam that is adjacent and at least partially overlapping the first spot beam. The platform may assign to the first spot beam a reserved combination of frequency and polarization during a first time period, and at second time, assign the reserved combination to the second spot beam. The platform may also assign the reserved combination simultaneously to adjacent spot beams by managing user of the reserved combination by geographically isolated terminals in the spot beams. The platform may further assign different portions of the reserved combination to adjacent spot beams without geographical limitations.

Abstract: This disclosure provides systems, methods and apparatus for multi-channel satellite calibration. In one aspect, a calibration system can provide a transmit calibration signal based on a reference calibration signal to a satellite. The satellite can transmit back a receive calibration signal that can be obtained by the calibration system. Sub-carriers of the receive calibration signal can be compared with sub-carriers of the reference signal to determine adjustments to transmission properties of antennas of the satellite.

Abstract: Electrically large, stepped-wall or smooth-wall, direct-radiating horn antenna apparatus that may preferably be used in satellite spot beam applications. Exemplary electrically large smooth-wall horn antenna apparatus comprises one or more input ports, an electrically large output port, and a smooth-wall or stepped-wall tapered section having a spline-shaped profile extending from the input port(s) to the output port of the apparatus. The spline-shaped profile is preferably monotonic and is preferably configured to generate a spot beam. The spline-shaped profile may be configured to support multiple frequency bands, and dual simultaneous polarization having either linear or circular polarization. The spline-shaped profile is defined by spline knots, and, the knot radii form a nondecreasing sequence. Preferably, the spline-shaped profile comprises a piecewise cubic Hermite interpolating polynomial spline that interpolates the shape of curves between the spline knots.

Abstract: A wide beam radio frequency (RF) antenna includes a waveguide and one or more electrically conductive protrusions. The waveguide has at least one electrically conductive interior wall surface, a boresight defined by a longitudinal axis, and an aperture plane, transverse to the longitudinal axis, disposed at a distal end of the waveguide. A first proximal portion of each protrusion is electrically coupled to the electrically conductive interior wall surface, a distal portion of the protrusion being outside the aperture plane.

Abstract: A multi-cavity RF filter has at least one electrically conductive coupling probe disposed between two resonator cavities. The coupling probe is provided with an ESD protective arrangement such that the coupling probe is electrically connected to a metallic housing of the RF filter only by the ESD protective arrangement. The ESD protective arrangement is configured to provide (i) a low resistance electrical path from the coupling probe to the metallic housing and (ii) a high impedance to RF energy having wavelengths proximate to a center frequency wavelength of the RF filter.

Abstract: A multiplexer includes a microstrip manifold, and a filter bank having at least two output filters. The multiplexer channelizes an input radio frequency (RF) band of electromagnetic energy into a set of output channels by way of the filter bank. The microstrip manifold has an input port that receives an input RF signal, and at least two output ports. The microstrip manifold distributes the input RF signal to each output port, each said output port being coupled to a respective one of the at least two output filters. The multiplexer may be an input multiplexer for a spacecraft communications payload system.

Abstract: A spacecraft has a high efficiency multi-beam antenna (MBA) system that serves a coverage region on the Earth. The coverage region subtends an angle, when viewed from the spacecraft, of at least ten degrees. The antenna system provides, within the coverage region, at least sixteen spot beams. A signal provided by the MBA system to each spot beam has a carrier to interference ratio (C/I) of no less than 20 dB. The system enables use of a three color frequency reuse scheme without recourse to signal encoding.

Abstract: Methods that test multibeam satellite communication systems, including its antennas and transponders. The methods use input power telemetry and output noise power to test satellite transponders and antennas while the satellite is in orbit. One method that tests a satellite receive antenna employs at least two earth stations, one for RF testing and one for telemetry and commanding, with each providing a backup for the other. Other methods may use one or more earth stations to perform testing. Methods are disclosed that generate receive antenna pattern measurements, transmit pattern measurements, input chain frequency response curves, input chain transfer curves, and output chain frequency response curves.

Abstract: A dual mode dielectric resonator (DR) filter has a first DR, and is configured to operate at a HE12? mode within a first frequency band while exhibiting a Q factor of no less than 5000. A first characteristic size of the first DR may be substantially similar to a size of a second DR, where the second DR is configured to operate in a conventional DR filter at a HE11? mode within a second frequency band, the second frequency band being substantially lower than the first frequency band.

Abstract: A spacecraft propulsion system has at least one chemical thruster, at least one electric thruster, a propellant supply arrangement that stores a propellant and a propellant conditioning arrangement configured to convert propellant into chemical species in a thermodynamic phase that can be readily ionized. The propellant is commonly supplied from the propellant storage device to each of the chemical thruster and the electric thruster. The chemical thruster has a gas generator and a high thrust accelerator; the electric thruster has a plasma generator and a high specific impulse accelerator. The propellant supply arrangement is configured to control flow of the propellant from the propellant supply arrangement to the gas generator and the propellant conditioning arrangement, and a first flow path connects propellant supply arrangement with the gas generator, and a second flow path connects propellant supply arrangement with the plasma generator.

Abstract: A solar panel has a number of rectilinear photovoltaic solar cells. Each solar cell has four edges, a current collector bar having at least two conductively coupled collector bar segments, and a grid of electrodes conductively coupled to the collector bar. A first collector bar segment is substantially parallel to and proximate to a first edge of the solar cell, a second collector bar segment is substantially parallel to and proximate to a second edge of the solar cell, the second edge being orthogonal with respect to the first edge. In some disclosed techniques, the solar panel has a string of solar cells disposed on a surface of the solar panel in a substantially spiral or serpentine manner and no solar cell within the string is electrically connected to another solar cell in the string by any means other than a cell interconnect.

Abstract: An RF feed element for an antenna system required to comply with a set of specified secondary pattern characteristics is designed by performing a quantitative optimization of the RF feed element directly with respect to the secondary pattern characteristics. The quantitative optimization may include pre-computing a plurality of partial secondary pattern complex field values. Each partial secondary pattern may be associated with an RF feed element modal beamlet. A value of at least one to-be-optimized feature is optimized by iteratively adjusting the value of the to-be-optimized feature(s) within an optimization loop that iteratively computes secondary pattern characteristics and compares them to the specified secondary pattern characteristics.

Abstract: Techniques for detachably joining a first component and a second component includes a band clamp, a tensioning device, a plurality of shoes, and a plurality of brackets. The band clamp is configured to cause the plurality of shoes to engage an abutting cylindrical flange of each of the first component and the second component and to provide a sufficient clamping pressure to join the first component with the second component. Each of the plurality of brackets is attached to one of the first component and the second component. The sufficient clamping pressure results from redundant, independently inspectable, sources, a primary redundant source being circumferential tension in the band clamp, caused by tightening the tensioning device, to produce a first radial restraining force on the shoes, and a secondary redundant source being a second radial restraining force, applied by way of the plurality of brackets, to the band clamp.

Abstract: Stored momentum on a spacecraft is managed by determining a target profile of stored momentum as a function of time for the spacecraft; measuring a difference between a momentum value actually stored on the spacecraft and a desired momentum value, where the desired momentum value substantially conforms to the target profile at a particular time; reducing the difference by producing a torque on the spacecraft, where the torque results from selectively controlling at least one solar array position offset angle, the offset angle being an offset of at least one solar array of the spacecraft from a nominal sun pointing direction.

Abstract: A novel Parametric Systematic Error Correction (ParSEC) system is disclosed which provides improved system accuracy for image navigation and registration (INR). This system may be employed in any suitable imaging system and, more specifically, to all imaging systems that exhibit systematic distortion. The ParSEC system may be employed to any such system regardless of sensing type (remote or in situ) or imaging media (photon or charged particle) and is further applicable to corrected imaging of any celestial body currently detectable to remove distortion and systematic error from the imaging system employed. The ParSEC system of the instant invention comprises a software algorithm that generates at least about 12 correction coefficients for each of the INR system measurements such as stars, visible landmarks, infrared (IR) landmarks and earth edges.

Abstract: A load current is limited to a safe level with a current protection logic circuit within a first selected interval after detection of a fault condition. The current protection logic circuit returns the load current to a normal level within a second selected interval after correction of the fault condition, wherein said safe level is less than one half of the normal level. The current protection logic circuit is a feature of a high side driver comprising at least two source drivers, each source driver being configured to switch an electrical load to a common power supply, and comprising a respective current protection logic circuit.

Abstract: Methods, systems and apparatus for ground-based beamforming of a satellite communications payload (200) within a satellite communications network (100). An embodiment of the invention comprises a satellite (11) communicatively coupled to at least one gateway (12) via a feeder link (13) and a plurality of user terminals (16), each communicatively coupled with the satellite by a user link (17) where a ground based beam forming system (400) receives, via feeder link (13), return path signals (452) traveling from the user terminals (16) via the satellite (11) to the at least one gateway (12) and forward path signals (457) traveling from the at least one gateway (12) via the satellite (11) to the user terminals (16), and measures and corrects amplitude and phase errors of the return path signals (452) and the forward path signals (457).

Abstract: A spacecraft payload element is rotated by a mechanism about virtual pivot point (VPP) substantially distant from the mechanism. The mechanism couples the payload element to a spacecraft main body structure, and has a four-bar linkage configured to rotate the payload element about a virtual pivot point (VPP). The VPP may be proximate to the focus or center of gravity (cg) of the payload element. Rotation of the payload element about the VPP may be controlled by linear or rotary actuators which drive the four-bar linkage. The four-bar linkage may be configured to provide a mechanical advantage to the actuator.

Abstract: A high capacity satellite having multiple aspect ratios is configured to have at least two modules. Each module includes a first panel and a third panel facing, in an on-orbit configuration, respectively, toward north and south and having a width in an east-west direction (EW width); and a second and a fourth panel oriented, in the on-orbit configuration, respectively, east and west and having a width in the north-south direction (NS width). Each module has a respective aspect ratio of EW width to NS width, a first module is configured with a first aspect ratio, a second module is configured with a second aspect ratio; and the second aspect ratio is substantially larger than the first aspect ratio. At least one antenna reflector is disposed, during launch, proximate to at least one of the first and third panel of the second module.

Abstract: Deorbiting of an earth-orbiting satellite is accomplished by executing an orbit transfer maneuver, the orbit transfer maneuver resulting in transference of the satellite from an operational orbit to a disposal orbit, where the disposal orbit is substantially circular and has a nominal radius of approximately, 31,000 kilometers. The operational orbit may be substantially geosynchronous and have at least one of (i) an inclination of greater than 10 degrees and (ii) a nominal eccentricity greater than 0.1. Alternatively, the operational orbit may be a medium earth orbit.