Abstract: EM field absorbing compositions, particularly lightweight magnetic and carbon loaded compositions. The composition finds particular use as a radar absorbing coating for structures. There are further provided coated surfaces comprising the composition, methods of absorbing EM radiation, and methods of use of such a composition, such that a surface coated in the composition is capable of absorbing EM radiation. An electromagnetic radiation absorbing composition comprising an admixture of carbon nanotubes present in the range of from 0.1 to 10 v/v % dried, magnetic particulates with an average longest dimension of at least 1 micron, present in the range of from 1 to 60% v/v dried, in a non-conductive binder; preferably the iron particulates are present in the range of from 15-30% v/v.

Abstract: The invention relates to ferromagnetic fibre composites, particularly ferromagnetic coated fibre plies in fibre reinforced polymer composites (FRPC), more preferably to a ferromagnetic FRPC, and composites with a plurality of functionalised fibre layers. The composite structure comprising at least one ferromagnetic fibre ply, wherein said ferromagnetic fibre ply is substantially encapsulated in a binder matrix to form a fibre reinforced polymer composite, wherein said at least one ferromagnetic fibre ply comprises a fibre ply and on at least one surface of said ply comprising at least one layer of a ferromagnetic material.

Abstract: There is disclosed A directional multi-band antenna, the antenna comprising: an optical unit comprising an optical sensor; an RF unit comprising an RF sensor; a substantially planar optical lens, the optical lens comprising surface relief elements for beam forming, the lens being arranged to focus optical signal beams, incident along a first optical axis, onto the optical sensor, the optical lens being substantially transparent to RF signals, an RF beam forming device arranged to receive RF signals incident along the first optical axis and focus such RF signals onto the RF sensor.

Abstract: An optical signal transmission apparatus (1) for a rotating antenna comprising a plurality of optical modulators (6) arranged for receiving a respective plurality of analogue RF signals (5) and for modulating a respective plurality of optical signals therewith to produce a plurality of modulated analogue optical signals (8). A plurality of opto-electrical converters (14) each converts a respective modulated analogue optical signal (13) into an analogue electrical signal. The plurality of optical modulators (6) are rotationally coupled in optical communication with the plurality of opto-electrical converters (14) via an optical rotary joint (10) including a reversion prism.

Abstract: A method and apparatus are provided to store transaction records in a retrievable form and to enable subsequent search and retrieval of stored transaction records. Transaction records are captured and then grouped according to predetermined grouping criteria such that they may be indexed to a first level and then efficiently compressed for bulk storage. In the event that records need to be retrieved subsequently, the first level index may be used to select one or more groups of records satisfying first level search criteria and, following retrieval of the selected groups from storage and de-compression, a second level index may be created to enable a more detailed record-level search for matching records in the retrieved groups. Preferably, the same indexing technique is used for both the first and second level of indexing.

Abstract: A differential transmission transition interface is disclosed which can include first and a second buried conducting tracks providing respectively first and second differential couplings between a differential RF transmission output and a waveguide; the first buried conducting track extending over an opening of the waveguide to provide a first RF coupling element; and the second buried conducting track extending over the opening to provide a second RF coupling element. At least a portion of the first RF coupling element extends over the waveguide opening in a first angular direction; and at least a portion of the second RF coupling element extends over the waveguide opening in a second angular direction that is opposed to the first angular direction.

Abstract: An antenna system, comprising: a phased array antenna (4); and a dielectric lens arrangement (6), for example a single solid dielectric lens (6) comprising a substantially spherical convex surface (12) and a concave surface (14); wherein the dielectric lens arrangement (6) is arranged to magnify the effective aperture of the phased array antenna (4). The concave surface (14) is positioned within the near field of the phased array antenna (4). The phased array antenna (4) is operated at a frequency greater than or equal to 50 GHz. The antenna system retains some ability to electronically scan the beam. The antenna system may be for transmission and/or reception. The antenna system may be used for example for communication between two vehicles.

Abstract: Methods and apparatus for producing and assessing at least part of an object (2), the methods comprise: performing, using Additive Manufacturing apparatus (8), an Additive Manufacturing process to produce a test specimen (30, 34, 38) and at least part of an object (2); performing, using micro-tomography apparatus (40), on the test specimen (30, 34, 38), a micro-tomography process to create a digital model (50) of the internal structure of the test specimen (30, 34, 38); determining whether or not the model (50) satisfies one or more criteria; and, if the model (50) satisfies the criteria, determining that the at least part of the object (2) produced by performing the Additive Manufacturing process is acceptable, or, if the model (50) does not satisfy the criteria, determining that the at least part of the object (2) produced by performing the Additive Manufacturing process is not acceptable.

Abstract: An antenna system (1) comprises a directional antenna (2) adapted to rotate through a range of directions in azimuth. It is responsive to radio-frequency (RF) signals received from directions within the range of directions in azimuth. A receiver (7) is arranged to receive the RF signals from the antenna within a signal frequency response band of the receiver and to provide a corresponding output for signal processing. A signal filter (11) is operable to block the output from the receiver when the frequency of the RF signal lies at a frequency within the signal frequency response band of the receiver and a detector unit (8) is arranged to apply the signal filter when the directional antenna is directed to a predetermined azimuth at which an interference source is located and to not apply the signal filter otherwise.

Abstract: A method of combining and co-aligning a plurality of radiation beams each having a respective waveband, includes the steps of passing each of said radiation beams to a respective lateral deflector to impart a selected lateral displacement to said beam. Each of said radiation beams with respective imparted lateral displacements is then passed to an optical collimating element which passes said radiation beams to an optical deflecting element which applies a wavelength dependent deflection to the radiation beams. The respective lateral displacements are selected having regard to the waveband of each beam to cause all to exit the optical deflecting element at the same angle so they are co-aligned.

Abstract: The structural health of a structure such as an aircraft is monitored by spraying a paint formulation containing a loading of carbon nanoparticles to provide a paint layer forming part of a paint system. The paint layer forms a smart skin whose electrical properties may be monitored to determine structural health.

Abstract: A radar or other microwave antenna comprises at least one antenna element, a feed structure for the element extending to the antenna element substantially normally thereto through a dielectric substrate, and characterized in that the dielectric substrate is anisotropic whereby to reduce unwanted common-mode currents in the feed structure. The anisotropy may be provided by elongate conductive elements distributed through the dielectric substrate and aligned with their longitudinal axes parallel to the feed structure.

Abstract: In apparatus for the acoustic transmission of power or data through a solid barrier such as a ships hull, assembly of an acoustic transducer to the hull is facilitated by bonding it first to an intermediate element by a thin layer of bonding adhesive and then bonding the intermediate element to the barrier using a second bonding layer. Acoustic matching of the transducer to the intermediate element is achieved by the thin layer, and the mechanically more robust base of the intermediate element can be rubbed on the barrier surface to displace or abrade away any unwanted debris or imperfections which might otherwise prevent the achievement of a thin second bonding layer. This makes the mounting and bonding process more tolerant of imperfections in the barrier surface due to either surface defects or particulate contamination. The transmit and receive transducers may be positioned relative to each other so as to suppress or attenuate multiple-transit signals.

Abstract: A display apparatus is described that comprises an optical ocular part (3) arranged for viewing a scene therethrough, and a waveguide display part (6) arranged for guiding image-bearing light to a transparent display output area (16) thereof and thereat displaying the image. The ocular part and/or the waveguide display part are positioned, or are arranged to be positioned, mutually in register for viewing simultaneously the scene with the displayed image incorporated in it, through the transparent display output area. A focuser part (17) positioned in register with the display output area focuses simultaneously the scene and the incorporated image for focussed viewing by a user (13).

Abstract: Disclosed is a method of mitigating the effects of anomalous propagation in a Radar system, comprising the steps of: receiving a plurality of returns from a plurality of transmit pulses; calculating a difference in magnitude between each of the plurality of returns and its successor; if one of the calculated differences indicates a first step change greater than a first predetermined threshold, calculating a first average magnitude of the returns received after the first step change, and replacing the returns received before the first step change with synthesised returns having a magnitude equal to the first calculated average magnitude.

Abstract: Disclosed is antenna sub-array for use in an antenna array comprising a plurality of such sub-arrays, comprising: a stripline for signal distribution, the stripline defining a plurality of signal pathways from a common feed point to a plurality of radiating elements, wherein the stripline is housed in a first support structure located a distance away from a first surface of a ground plane structure.

Abstract: A method and apparatus for selecting a value or change in value of a measurement variable for an observation of an object, comprising: receiving models for the object defined in terms of an observation parameter and a measurement variable; selecting values of the measurement variable; for each model, determining a value of the observation parameter for each selected value; for each selected value, determining a value of an expected classification potential level using the determined values; and selecting a value of the measurement variable dependent upon the potential level values; wherein the potential level is an expected level of: the information or lack of information, and/or the certainty or uncertainty, with which the object could be classified if a measurement of the observation parameter were taken of the object at the respective value of the measurement variable.

Abstract: Apparatus and a method for forming a metallic component by additive layer manufacturing are provided.

Abstract: A method for calibrating an antenna system (1) including a antenna elements (3) connected to signal receiver units (4) at an RF signal input port thereof comprising, generating an RF calibration signal (62), applying the RF calibration signal to the RF signal input port of the signal receiver units without applying the calibration signal via the antenna elements (3). The response of the antenna system to the calibration signal is measured, and a signal correction is calculated according to the measured response. The signal correction is applied to the response of the antenna system to signals subsequently received at the signal receiver units via the antenna elements of the antenna system.

Abstract: A pulse radar range profile motion compensation method (10) comprises: acquiring receiver samples (12); acquiring an estimate of the range rate of a target (14); removing an additional phase acquired by the echo signals; removing a shift in range cells of the receiver samples (18); applying a pulse Doppler filter (22); identifying the peak Doppler frequency and calculating a shift from zero of the peak Doppler frequency (24); calculating a range rate correction (26); adding the range rate correction to the estimate of the range rate and repeating the removal of the additional phase (16) and the shift in range cells (18), and using the new range rate estimate to obtain motion compensated receiver samples (28); and generating an output signal indicative of the motion compensated receiver samples for generating a range profile (30).