Abstract: An apparatus for controlling the gain and phase of an input signal input to a power amplifier comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output by the power amplifier, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The phase control loop delays the first signal such that the delayed first signal and the second signal used to obtain the error signal correspond to the same part of the input signal. The apparatus may be included in a satellite.

Abstract: An apparatus for controlling the gain and phase of an input signal input to a power amplifier comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output by the power amplifier, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The phase control loop delays the first signal such that the delayed first signal and the second signal used to obtain the error signal correspond to the same part of the input signal. The apparatus may be included in a satellite.

Abstract: An apparatus for controlling the gain and phase of an input signal input to a power amplifier comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output by the power amplifier, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The phase control loop delays the first signal such that the delayed first signal and the second signal used to obtain the error signal correspond to the same part of the input signal. The apparatus may be included in a satellite.

Abstract: An apparatus for controlling the gain and phase of an input signal input to a power amplifier comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output by the power amplifier, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The phase control loop delays the first signal, such that the delayed first signal and the second signal used to obtain the error signal correspond to the same part of the input signal. The apparatus may be included in a satellite.

Abstract: An article comprises a carbon fibre reinforced plastic (CFRP) substrate, a buffer layer disposed adjacent the substrate, the buffer layer comprising a poly(para-xylylene) polymer; and a moisture barrier coating disposed adjacent the buffer layer.

Abstract: A phased array antenna for providing a radiation pattern having at least one communication beam, includes a plurality of antenna elements, each with an antenna element signal having a phase relationship and an amplitude relationship to the other element signals; a digital signal processing arrangement providing a digital beamforming network; and an analog beamforming network arranged to reduce exposure of the digital signal processing arrangement to an interfering signal. Analog beamforming weights are selected to generate a null in the radiation pattern in a direction corresponding to the interfering signal.

Abstract: A multi-band filter is disclosed which includes an input manifold; an output manifold; and a plurality of filters connected in parallel between the input manifold and output manifold. The filters have a first section proximal to the input manifold which is matched to the input manifold and a second section proximal to the output manifold which is matched to the output manifold.

Abstract: A structure for guiding electromagnetic radiation, including: a substrate; a waveguide provided on the substrate and having a first end for receiving electromagnetic radiation and a second end; and an anti-reflection region provided at the second end of the waveguide on the substrate, the length and the width of the anti-reflection region being optimised to suppress back reflection of radiation that reaches the second end.

Abstract: There is provided an apparatus for a satellite communication system comprising: a processor to determine at least one out of a phase offset for a frequency channel of a plurality of frequency channels demultiplexed from a carrier to compensate for group delay variation within the carrier and a gain offset for the frequency channel to compensate for gain variation within the carrier, wherein the processor is further configured to apply the at least one out of the determined phase offset and gain offset to the frequency channel before the carrier is reformed from said plurality of frequency channels. The invention therefore provides a way of digitally compensating for any undesired gain and group delay introduced by, for example, analogue components such as filters in the satellite communication system.

Abstract: An antenna feed assembly is provided which includes at least two elongate feed chains lying adjacent one another. Each feed chain is adapted to transmit or receive electromagnetic radiation between itself and the antenna along a longitudinal feed axis thereof via a transmit/receive element. The feed chains are held in fixed lateral relationship to one another by first and second mountings spaced apart axially of the feed chains. The transmit/receive elements extend axially from the first mounting towards the antenna and the second mounting is positioned on a side of the first mounting remote from the antenna. The first mounting has a lower coefficient of thermal expansion in the lateral direction than the second mounting whereby translational movement of each transmit/receive element in the lateral direction owing to temperature change of the assembly will be reduced.

Abstract: A thermal control film for use in spacecraft having a multi-layer interference filter adapted to exhibit high reflectivity to solar radiation, low absorptivity across the microwave spectrum and high emissivity in the far infra-red. The film is free from metal and extends over the active face of an antenna carried by the spacecraft. Such a film exhibits the desired thermo-optical properties for a thermal control radiator surface and can be used over the active face of a communications or radar antenna without disrupting the RF signal.

Abstract: A telecommunications satellite payload processing system having one or more identical generic integrated processor modules is provided. The number of integrated processor modules can be selected in accordance with the antenna and bandwidth characteristics of a specified mission uplink and downlink in relation to the characteristics of the integrated processor module.

Abstract: There is provided an apparatus for calibrating a multi-beam satellite system comprising a beam forming network providing a plurality of signal paths, the apparatus comprising a calibration processor for determining the phase and amplitude shift of a test path relative to a reference path, the calibration processor being configured to determine the phase and amplitude shifts of the test path relative to the reference path for at least two calibration tones of at least two different frequencies to allow a phase and amplitude offset of the test path for a signal of any frequency within an operational frequency range of the multi-beam satellite system to be calculated.

Abstract: The invention relates to active interference suppression in a satellite communication system, particularly but not exclusively to an apparatus and method for using active interference suppression in order to suppress co-channel interference between user signals in the communication system. The communication system includes a receive or transmit antenna having a plurality of antenna elements, each antenna element associated with a respective antenna element signal. The method includes the steps of calculating complex weighting values for one or more of a plurality of beam signals, adjusting the beam signals in accordance with the calculated complex weighting values and cancelling co-channel interference in at least one of the beam signals using the one or more adjusted derived beam signals to provide an interference suppressed output signal. The complex weighting values can be calculated based on a constant modulus algorithm.

Abstract: An optical element is disclosed which includes transparent superconductor material.

Abstract: An apparatus for an antenna system comprising one or more blades for splitting the electromagnetic field received by an antenna into a plurality of sections corresponding to separate beams and redirecting said plurality of sections for detection by a plurality of detectors. The apparatus may comprise a plurality of blades for splitting the field into successively smaller and smaller portions. The plurality of detectors can be positioned outside the focal region of the antenna system. The apparatus may further comprise focusing means for focusing the sections of the field onto another blade or a detector. There is also provided an antenna system comprising a plurality of feed horns for producing a plurality of beams; and a plurality of elements for redirecting said beams towards a focal region of the antenna system so as to form a group of closely packed beams for transmission by the antenna system.

Abstract: In order to maintain isolation of signals within a multiport amplifier of a communications satellite and to reduce cross-talk components, by monitoring communications signals passing through the multiport amplifier, output signals of the multiport amplifier are sensed and downconverted to baseband, and applied to an emulator mechanism of the multiport amplifier. The emulator mechanism comprises a reverse matrix of the multiport amplifier, which recovers the input signals of the multiport amplifier together with cross-talk components, and a digital signal processor which carries out a frequency analysis of the cross-talk components by means of an FFT, and employs a digital model of the multiport amplifier to determine the state of the multiport amplifier which gives rise to such cross-talk components. The digital signal processor may be located at a ground station to which communication is made via a telemetry link.

Abstract: A method is disclosed for filtering communications channels in a telecommunications satellite to remove large unwanted interfering signals, which includes monitoring channels of an uplink signal by stepping across a channel with a first analog agile filter having a narrow bandwidth in relation to the channel, and at each step monitoring the signal within the channel step, in order to determine the presence of interfering signals, and configuring a second analog agile filter having an adjustable band stop function to block the interfering signals. The uplink signal has first and second signal paths for the uplink signal, and the method includes demultiplexing the channels of the uplink signal onto separate lines in the first path, carrying out the band stop function within the second signal path, and replacing with the remaining filtered part of the channel, by a switching operation, the demultiplexed version of the channel.

Abstract: An output multiplexer OMUX is disclosed which includes a plurality of hybrid-coupled filters. Each hybrid-coupled filter may be arranged to receive a first signal and a second signal via first and second input ports respectively, and output the first signal and the second signal via first and second output ports respectively, and the hybrid-coupled filters may be connected to combine a plurality of the first signals into a first multiplexed signal and combine a plurality of the second signals into a second multiplexed signal.

Abstract: A waveguide is provided that includes an elongate dielectric inner region, and an electrically conducting outer region spaced apart from the dielectric inner region. The dielectric inner region may be arranged to be flexible, and in some examples may be formed from powdered dielectric contained in a polymer tube or matrix, or in other examples may be formed from a plurality of segments. In some examples of the waveguide, each segment may be formed to have lenticular end faces, and may be formed from sintered BaTi4O9.