Abstract: A polariser particularly suitable for use in receiving satellite television signals includes a ferrite rod located within a waveguide, a yoke co-extensive with the ferrite member and a coil wound around the yoke. The yoke preferably is "U" shaped and includes an arm which projects into the waveguide at the end of the ferrite rod remote from the input of the waveguide.

Abstract: A semiconductor arrangement includes a substrate having a plurality of transistors formed therein and a tungsten layer thereon in the form of elongate tracks serving to interconnect the transistors. Localized regions of highly doped semiconductor material underlie the tracks and form an ohmic contact therewith. The tungsten layer is overlaid with an electrically insulating oxide on which further electrical interconnections are present.

Abstract: In a method of manufacturing a member having a cross-sectional area which varies along its length, the member is produced by filling a cavity 6 in a die 5 with powdered material and compressing it. The die includes portions 8, 9 and 10 at different heights around the opening 7 so as to enable the amount of powdered present in the cavity to be varied along its length without compromising the shape of the final item to be manufactured.

Abstract: A method of joining components by soldering comprising forming discrete layers of silver (13, 17) and another metal (19), e.g. a tin or indium based material, the two layers having volumes in a ratio different from that in the eutectic alloy formed by silver and that metal, and raising the temperature of the layers above the melting point of the eutectic alloy for a period sufficient to cause initially formation of the eutectic alloy and then, by reaction between the eutectic alloy and one or other of silver and the other metal, formation of a material having a melting point higher than the eutectic alloy melting point. The method allows soldering, e.g. of a silicon wafer (1) to a header (3), at a relatively low temperature below that which the joint will withstand after formation.

Abstract: A high-speed digital to analogue convertor includes a matrix of cells each including a current source, in which there are provided local decode circuitry within each cell to bring into operation simultaneously all those current sources required to decode any one value.

Abstract: A semiconductor device having a sapphire substrate on which is formed a localized island of polysilicon, the island having side walls which extend away from a surface of the substrate. A field effect transistor is formed in the island and a doped polysilicon fillet is interposed between the gate region and the substrate. In addition the electrical potential of the polysilicon fillet is controlled with respect to the source region. The control of the electrical potential enables the premature turn on characteristics of the device to be reduced by the polysilicon fillet forming a secondary gate electrode on the side walls, and because these secondary gates are at source potential the parasitic edge transistor present in the side wall is always turned off. A modified device has an independent side gate bias arrangement.

Abstract: A method of brazing a silicon component to a molybdenum and/or tungsten component wherein prior to brazing the surface of the molybdenum and/or tungsten component is first provided with a thin gold coating and then a coating of palladium, platinum or rhodium. This allows satisfactory brazing to be effected using conventional aluminum-based brazes at temperatures below 650.degree. C.

Abstract: A method of forming a plurality of MIM capacitors is provided in which one of the metal layers constitutes a plurality of electrodes and a plurality of beam- leads. Each beam- lead is contiguous with the dielectric layer and the substrate. Preferably the substrate is transparent so as to facilitate the separation of the capacitors.

Abstract: Waveguide apparatus in which a dielectric substrate is placed between sections of a waveguide. The dielectric substrate incorporates slots arranged in a linear fashion and having extended portions, there being a narrow gap between adjacent slots. This enables accurate control of radiation losses through the dielectric layer sandwiched between the sections of the waveguide to be achieved.

Abstract: Encryption apparatus mainly intended for encrypting speech signals samples a signal to be encrypted at two differing rates, and reads the sampled signal into storage means at one of said rates and reads it out of said storage at the other of said rates so that the signal is alternately dispersed upwardly and downwardly with each pair of upward and downward dispersion representing a frame. To improve security the apparatus further generates a pseudo random binary number, defines a superframe structure consisting of a predetermined number of said frames, and sets the starting point of each individual superframe as an upward or a downward dispersion in dependence on the next digit of said pseudo-random binary number.

Abstract: Electrical conductor arrangement consists of a lamina of ceramic, such as alumina, which has copper foils bonded to both faces. The foils are of different thicknesses, and they are bonded at a high temperature, so that on cooling the ceramic lamina adopts a curved profile. By mounting the lamina with the convex surface mounted towards a heat sink, it can be clamped at its edges to ensure a good thermal contact over the whole of its surface.

Abstract: A semiconductor arrangement has a substrate which carries a partially filled array of semiconductor cells, and utilises the vacant sites in the array to position interconnecting tracks. A filled array is manufactured, and when the electrical function of the arrangement has been allocated, those semiconductor cells, each of which contains active semiconductor devices, which are not needed to perform the allocated function are removed. The vacant sites so formed are then occupied by electrically conductive tracks. The arrangement is suitable for silicon-on-sapphire gate arrays.

Abstract: In a thin film circuit, high values of resistance/surface area can be attained by forming the resistive material as a mesh rather than a solid block. The advantages of this are that it gives a high resistance value in a small area and allows laser trimming, both without adversely affecting resistor characteristics such as stability.