Abstract: Apparatus for generating spin waves comprising a body (102) of magnetic material and an elastic wave generator (120), wherein the body (102) has a surface (108) and the elastic wave generator (120) is arranged to transmit elastic waves so that they propagate through the body (102) towards the surface (108) and are reflected at the surface to form a standing elastic wave in the body (102), thereby generating spin waves.

Abstract: Apparatus for generating spin waves comprising a body (102) of magnetic material and an elastic wave generator (120), wherein the body (102) has a surface (108) and the elastic wave generator (120) is arranged to transmit elastic waves so that they propagate through the body (102) towards the surface (108) and are reflected at the surface to form a standing elastic wave in the body (102), thereby generating spin waves.

Abstract: Apparatus for generating spin waves comprising a body (102) of magnetic material and an elastic wave generator (120), wherein the body (102) has a surface (108) and the elastic wave generator (120) is arranged to transmit elastic waves so that they propagate through the body (102) towards the surface (108) and are reflected at the surface to form a standing elastic wave in the body (102), thereby generating spin waves.

Abstract: A fluid conduit comprises a wall defining a fluid flow path and a confinement feature within the wall and being configured to confine energy within a cavity, wherein at least a portion of the fluid flow path extends through the cavity. The confinement feature may be configured to confine electromagnetic energy. The fluid conduit may comprise an oscillator defined by the cavity and a positive feedback arrangement. The fluid conduit may be configured for sensing a property of a fluid present in or flowing through the fluid conduit or for use in sensing a property of a fluid present in or flowing through the fluid conduit.

Abstract: A fluid conduit (2) comprises a wall (4) defining a fluid flow path (6) and a confinement feature (24) within the wall (4) and being configured to confine energy within a cavity (26), wherein at least a portion of the fluid flow path (6) extends through the cavity (26). The confinement feature (24) may be configured to confine electromagnetic energy. The fluid conduit (2) may comprise an oscillator defined by the cavity (26) and a positive feedback arrangement (34). The fluid conduit (2) may be configured for sensing a property of a fluid present in or flowing through the fluid conduit (2) or for use in sensing a property of a fluid present in or flowing through the fluid conduit (2). More specifically, the present invention deals with a microwave cavity sensor wherein the cavity member (24) is embedded in the wall (4) of the fluid conduit (2), the wall (4) including a composite region (20).

Abstract: A wind turbine and generator arrangement comprises a turbine that drives a self-excited induction generator via a shaft and mechanical gearbox. The induction generator includes an electrical circuit that includes a variable capacitance and a variable resistance. The variable capacitance may be constituted by a fixed capacitor and a triac under the control of a controller, or by a bank of capacitors switched by a relay under control of the controller. The variable resistance includes a triac controlled resistor or a bank of relay-switched resistors which constitute heating elements for heating domestic hot water. In use the generator frequency and voltage are allowed to ‘float’ while the optimal generator power output is maintained, but adjusting the impedance of the electrical circuit as the wind speed varies.

Abstract: A fluid conduit comprises a wall defining a fluid flow path and a confinement feature within the wall and being configured to confine energy within a cavity, wherein at least a portion of the fluid flow path extends through the cavity. The confinement feature may be configured to confine electromagnetic energy. The fluid conduit may comprise an oscillator defined by the cavity and a positive feedback arrangement. The fluid conduit may be configured for sensing a property of a fluid present in or flowing through the fluid conduit or for use in sensing a property of a fluid present in or flowing through the fluid conduit.

Abstract: Target sensor comprising: sensor probe having a resonance frequency that changes as the separation of the sensor probe and a target changes. Oscillator arranged to apply a radio frequency (RF) signal to the sensor probe, the oscillator having: control circuitry configured to regulate the frequency of the RF signal applied to the sensor probe to below the resonance frequency of the sensor probe. Detector arranged to detect an electrical characteristic of the oscillator that varies with the impedance of the sensor probe indicating an interaction of the sensor probe with the target.

Abstract: A fluid conduit (2) comprises a wall (4) defining a fluid flow path (6) and a confinement feature (24) within the wall (4) and being configured to confine energy within a cavity (26), wherein at least a portion of the fluid flow path (6) extends through the cavity (26). The confinement feature (24) may be configured to confine electromagnetic energy. The fluid conduit (2) may comprise an oscillator defined by the cavity (26) and a positive feedback arrangement (34). The fluid conduit (2) may be configured for sensing a property of a fluid present in or flowing through the fluid conduit (2) or for use in sensing a property of a fluid present in or flowing through the fluid conduit (2). More specifically, the present invention deals with a microwave cavity sensor wherein the cavity member (24) is embedded in the wall (4) of the fluid conduit (2), the wall (4) including a composite region (20).

Abstract: A target or rotor blade clearance measurement device is disclosed for indicating an interaction of a measurement probe with a target or rotor blade. In a preferred embodiment, the measurement device comprises a measurement probe containing a coil, a frequency source arranged to apply an input alternating signal to the measurement probe, and a frequency regulator arranged to regulate the input alternating signal at a frequency below the resonance frequency of the measurement probe. A detector is arranged to detect an output signal from the measurement probe at a frequency of the frequency source which varies in amplitude with an admittance and resonance frequency of the measurement probe. A circuit is arranged to scale the amplitude of the output signal detected by the detector according to the amplitude of the input signal provided by the frequency source.

Abstract: An electrical, magnetic or electromagnetic delay line self oscillator is described with a delay line arrangement, an oscillator control circuitry, and a frequency selection impedance connecting the delay line arrangement and the oscillator control circuitry and presenting an impedance to the delay line arrangement. The oscillator control circuitry includes an amplifier, a non linear amplitude control element (N-LACE) such as an active device with a negative differential conductance that provides an output amplitude has a negative second derivative with respect to an input signal, and a driver. The modal characteristics of electromagnetic delay lines can thus be exploited across a wide range of instrumentation applications, and a means is provided to enhance the achievable functionality and/or performance of the instrumentation without the need for expensive additional electrical hardware or electronics.

Abstract: Apparatus comprising: a radio frequency (RF) Robinson oscillator comprising: a resonator comprising a sensor rhumbatron, the sensor rhumbatron comprising a cavity member, the cavity member having a re-entrant boss member, the re-entrant boss member being arranged to project into a cavity portion of the cavity member; a feedback element arranged to provide positive radio frequency (RF) feedback to the cavity member thereby to increase a quality factor Q of the cavity member, the feedback element having first and second terminals coupled to the cavity member, the apparatus being operable to cause the oscillator to oscillate at a resonant frequency; and an output arranged to provide a signal that varies according to a value of at least one electrical parameter of the oscillator, said at least one electrical parameter being selected from amongst an electromagnetic loss and a resonant frequency.

Abstract: A mechanical oscillator arrangement includes a mechanical structure (30) having at least one transmission path through it, and at least one mode. A controller (40) is provided with an amplifier (70) and a feedback network (80, 90) which together provide a positive feedback oscillator for exciting a mode of the mechanical structure (30). The feedback network (80, 90) comprises a non linear amplitude control element (N-LACE) (90), a frequency dependent gain element with an electronic transfer function, and a phase compensator (80). The mechanical oscillator arrangement also includes an actuator (606) which excites the mechanical structure (30) based upon an output from the controller (40), and a sensor (60a) which senses vibrations in the mechanical structure (30) and then outputs a signal to the controller (40) based upon the sensed vibrations.

Abstract: An acoustic oscillator arrangement includes an acoustic system having at least one acoustic transmission path through it, and at least one mode. The acoustic transmission path is of variable length. A controller is provided with an amplifier and a feedback network which together provide a positive feedback oscillator for exciting a mode of the acoustic system. The feedback network comprises a non linear amplitude control element (N-LACE), a frequency dependent gain element with an electronic transfer function, and a phase compensator. The acoustic oscillator arrangement also includes an acoustic transmitter which launches an acoustic signal into the acoustic system based upon an output from the controller, and an acoustic receiver which receives an acoustic signal from the acoustic system which is fed back to the controller.

Abstract: An electrical, magnetic or electromagnetic delay line self oscillator is described with a delay line arrangement, an oscillator control circuitry, and a frequency selection impedance connecting the delay line arrangement and the oscillator control circuitry and presenting an impedance to the delay line arrangement. The oscillator control circuitry includes an amplifier, a non linear amplitude control element (N-LACE) such as an active device with a negative differential conductance that provides an output amplitude has a negative second derivative with respect to an input signal, and a driver. The modal characteristics of electromagnetic delay lines can thus be exploited across a wide range of instrumentation applications, and a means is provided to enhance the achievable functionality and/or performance of the instrumentation without the need for expensive additional electrical hardware or electronics.

Abstract: A self-oscillating remote sensor device includes a delay-line sensor system having at least one delay-line and at least one sensor element. The device also includes an oscillator control circuitry, and a frequency selection impedance connecting the delay-line sensor system and the oscillator control circuitry and presenting an impedance to the delay-line sensor system. The oscillator control circuitry includes an amplifier, a non linear amplitude control element (N-LACE) such as an active device with a negative differential conductance that provides an output whose amplitude has a negative second derivative with respect to an input signal, and a driver. Such a device permits successful interaction between electrical sensors and controlling (driving) electronics over long distances without the problems normally encountered when a delay-line is presented between an electrical sensor and its driver electronics.

Abstract: There is described a position sensor comprising a sensor electromagnetic field generator, a screen arranged to confine the sensor electromagnetic field, and an output. The output is arranged to provide a signal which varies in dependence upon an amount of flux compression of the electromagnetic field resulting from the presence of the screen. The amount of flux compression is related to a position of the screen in relation to the sensor electromagnetic field generator. There is also described a method of detecting a relative position of an electromagnetic field generator and a screen.

Abstract: Apparatus comprising: a radio frequency (RF) Robinson oscillator comprising: a resonator comprising a sensor rhumbatron, the sensor rhumbatron comprising a cavity member, the cavity member having a re-entrant boss member, the re-entrant boss member being arranged to project into a cavity portion of the cavity member; a feedback element arranged to provide positive radio frequency (RF) feedback to the cavity member thereby to increase a quality factor Q of the cavity member, the feedback element having first and second terminals coupled to the cavity member, the apparatus being operable to cause the oscillator to oscillate at a resonant frequency; and an output arranged to provide a signal that varies according to a value of at least one electrical parameter of the oscillator, said at least one electrical parameter being selected from amongst an electromagnetic loss and a resonant frequency.

Abstract: A wind turbine and generator arrangement comprises a turbine that drives a self-excited induction generator via a shaft and mechanical gearbox. The induction generator includes an electrical circuit that includes a variable capacitance and a variable resistance. The variable capacitance may be constituted by a fixed capacitor and a triac under the control of a controller, or by a bank of capacitors switched by a relay under control of the controller. The variable resistance includes a triac controlled resistor or a bank of relay-switched resistors which constitute heating elements for heating domestic hot water. In use the generator frequency and voltage are allowed to ‘float’ whilst the optimal generator power output is maintained, but adjusting the impedance of the electrical circuit as the wind speed varies.

Abstract: A rotor blade sensor for detecting a rotor blade (430) comprising an electrical oscillator arranged to generate an oscillating signal. An antenna (300) includes a coil (100) having one or two winding layers coupled to the electrical oscillator. The antenna (300) may instead or as well include a coil (100) comprising a plurality of winding layers, each layer being separated by al spacer for substantially reducing inter-layer capacitance, being coupled to the electrical oscillator. The antenna (300) is driven in use by the oscillating signal of the oscillator at substantially a resonant frequency of the antenna (300). The antenna generates an antenna electromagnetic field that interacts with a rotor blade (430) such that the electrical characteristics of the antenna (300) vary as the interaction between the antenna (300) and the rotor blade changes and a detector circuit is arranged to monitor these electrical characteristics.