Abstract: A length of microstrip line turns through successive right-angle corners to form a rectangular pattern comprising successive quartets of such corners. Each right-angle corner radiates with a polarization which is predominantly diagonal, and the strip lengths between the corners of each quartet are made such, in relation to the operating wavelength in the strip, that the radiation from each quartet sums to produce a desired polarization direction, e.g. vertical, horizontal, or circular of either hand. Some forms of the invention can be used in a resonant as well as a travelling-wave mode, the latter giving a main lobe whose direction sweeps with frequency.

Abstract: An ultrasonic flaw detection system automatically measures attenuation of an input signal from a receiver transducer that provides a reference level. Successive amplifier stages having stepped gains provide graduated output levels that are detected and stored by individual peak readers. Sampled output levels are compared in comparators and with a reference voltage generated by a digital-to-analog converter to produce a binary output corresponding to each signal as a first coarse attenuation level. Logic control and timing circuitry selects the output level corresponding to one of the signals having a peak voltage in a predetermined range. A logarithmic converter and comparator provide a fine attenuation reading which is summed with the coarse reading in digital form. This is decoded and displayed as a total attenuation readout.

Abstract: A method of fabricating a field effect transistor comprising the steps of forming an active layer of semiconductor material (GaAs) over a surface of a first substrate of semiconductor material (GaAs), applying a second substrate of insulating material, e.g. glass, over the surface of the active layer, removing the first substrate so that the active layer is now supported on the insulating second substrate, and forming source, drain and gate electrodes over the free surface of the active layer. To facilitate removal of the GaAs first substrate by selective etching, a buffer layer of GaAlAs resistant to the GaAs etchant, may be formed between the active layer and the first substrate, which buffer layer is removed, following removal of first substrate, using a selective etchant to which the GaAs active layer is resistant. The technique is particularly applicable to high frequency FETs requiring a very thin active channel region interfaced to a substrate having good insulating properties.

Abstract: A method of fabricating a field effect transistor comprising the steps of forming an active layer of semiconductor material, e.g. GaAs over the surface of a first substrate of semiconductor material, e.g., also GaAs, forming source, drain and gate electrodes over the surface of the active layer, applying a second substrate of insulating material to the surface of this structure, and removing the first substrate. To facilitate the removal of the GaAs first substrate by selective etching, a buffer layer of GaAlAs resistant to the GaAs etchant may be formed between the first substrate and active layer, which buffer layer is removed, following removal of the first substrate, using a selective etchant to which the GaAs active layer is resistant. A second gate electrode may be formed on the active layer following removal of the first substrate. The technique is particularly applicable to high frequency FET devices.

Abstract: Scanning radiation source detecting apparatus, comprising means for deriving a general response signal in response to radiation from any part of a field of view, and a central response signal in response to radiation from a central part of the field of view, with means for producing audio signals of a frequency dependent on the magnitude of the central response signal. The apparatus may produce a constant frequency signal in response to the general response signal, and the central response signal may be derived from the general response by a gate circuit controlled by a scanning mirror mechanism. The gate circuit may be connected to a voltage controlled oscillator by a sample-and-hold circuit or, by an integrating circuit. Alternatively the apparatus may comprise a light emitting diode energized by a radiation detector, an optical system arranged to form an image of the diode and two separate detectors placed in the optical system to form the general response and central response signals.

Abstract: A method of fabricating a field effect transistor comprising the steps of forming an active layer of semiconductor material, e.g., GaAs, over a surface of a first substrate of semiconductor material, e.g., also GaAs, forming a gate electrode on the surface of the active layer, applying a second substrate of insulating material to the surface of this structure, removing the first substrate, and forming source and drain electrodes on the opposite surface of the active layer to the gate electrode. To facilitate removal of the GaAs first substrate by selective etching, a buffer layer of GaAlAs resistant to the GaAs etchant, may be formed between the active layer and the first substrate, which buffer layer is removed, following removal of the first substrate, using a selective etchant to which the GaAs active layer is resistant. A second gate electrode may be formed on the opposite surface of the active layer to that on which the first gate electrode is formed.

Abstract: An accelerometer includes a thermocouple circuit which comprises a movable member and a second member which abuts the movable member, wherein the abutting parts of the members include a cutting portion and wherein said parts are composed of dissimilar metals, for example steel and tungsten carbide, and recording means connected to the members for recording a thermoelectric signal generated when the cutting portion cuts the abutting part of the other member during acceleration.

Abstract: A fascine capable of conforming to the contours of a supporting surface, comprises a core of loose cylindrical pipes disposed within a surrounding sleeve of similar pipes transversely and continuously inter-connected by flexible ties. Binding straps attached to the sleeve are reeved so as to cause axial pleating of the sleeve when tensioned, thereby to bind the core into rigid cylindrical form. The fascine is transported in bound condition and the binding straps slackened on deployment.

Abstract: A sliding breech block suitable for rapid, semi-automatic operation of a bag charge gun comprises two interlinked portions mutually engageable in two dispositions at a stepped interface one of the portions being drivable in a transverse guideway by gun runout via a crank and a shaft, and the other portion being guidable by rollers engaged in cam tracks to follow a semi-arcuate path aligned at one end with the gun barrel axis and at the other with the guideway axis.

Abstract: An apparatus for transferring television pictures onto cine film which operates independent of field scan frequency and which synchronizes each frame of the cine film with the television field scans to avoid the appearance of a bar across each frame. The apparatus comprises a cine camera which in operation is placed in front of a television screen and which generates a shutter opening signal, a control unit which synchronizes that signal with the video signal to the television such that the shutter opens at the beginning of a field scan, and a motor drive unit which utilizes the video signal to drive the camera shutter blade at one third the field scan frequency. The apparatus is useful for transferring television field scans operating at any frequency onto cine film.

Abstract: A fuel tank largely filled with a plurality of discrete impermeably walled cells, the cells and the space between them and the tank sides and roof being substantially filled with fire protective reticulated structure. The cells are each plugged into one of a plurality of fuel collection networks, via non-return valves which prevent return flow of the fuel into the cells. The region between the cells and the tank walls is arranged to receive incoming fuel which then flows from the ullage into the cells, and, by means of a self switching pump, is also arranged to empty preferentially. The purpose of the invention is to minimize fuel loss and fuel fire in the event of a tank rupture.

Abstract: A decompression bubble detector comprises a pulsed ultra-sound transmitter/receiver which is scanned across a cross-section of tissue and the total number of pulse echoes received in a preselected time interval is recorded. Changes in the total number of pulse echoes recorded in successive time intervals are used to monitor the decompression. A single transducer is scanned by means of a driven eccentric cam and a cam follower. A sin/cos potentiometer generates a signal related to the angular position of the transducer connected to a delay so that pulse counting can be arranged to coincide with the passage of the transducer across the target.

Abstract: A radio communications system for aircraft, particularly useful at UHF frequencies and in aircraft travelling at high speed and low level where rapid phase and amplitude fluctuations degrade intelligible speech transmission. The system comprises a transmitter in a first aircraft, the transmitter including an upshift frequency translator for transferring the frequency band of an input signal from a microphone to a higher band, and further including an amplitude modulator for modulating the frequency translated signals; and a receiver in a second aircraft arranged to receive and demodulate the transmitted signals, the receiver including a high pass filter for removing noise from the demodulated signal, and a downshift frequency translator for transferring the frequency band of the filter output to a lower band.

Abstract: A time delay and integrate signal processing device is provided to which, in use, a clock signal having a duty cycle which varies linearly with time at a predetermined rate is applied at an input. The number of delay stages in the path of signals from a plurality of input taps is determined in accordance with a predetermined function of the rate of change of the clock duty cycle.Embodiments of the invention may be employed to advantage in SONAR applications where signals are received from a plurality of transducers to scan a sector by constructive summation of signal returns. The predetermined function may be chosen to minimize distortion during a scan and so scanning may take place at a higher rate than with prior art devices enabling full coverage of the sector with good range resolution to be achieved with a single device.

Abstract: In a method of fabricating semiconductor devices, eg infra-red charge coupled devices (IRCCDs), the invention relates to the provision of a region containing a first species of ionized dopant with a body of semiconductor material in which the device is being fabricated, in which diffusion of this ionized dopant creates an internal electric field which provides a barrier against the penetration of a second relatively faster-diffusing species of ionized dopant into a selected region of the semiconductor body. In the method described in its application to the fabrication of a monolithic IRCCD, the second species of ionized dopant is introduced into detector regions of the body of semiconductor material to render them sensitive to infra-red radiation, and the barrier provided by diffusion of the first species of the ionized dopant serves to prevent the penetration of the second dopant species into the active charge storage and transfer channels of the CCD.

Abstract: A Panel Breaking Apparatus comprising at least one fusible conductor having at least one region of increased fusibility and embedded in intimate contact with the panel material and connected to a source of electrical power operable to produce a high-energy pulse of current sufficient to fuse the conductor and thus to break the panel.

Abstract: An acoustic wave device comprises a substrate carrying two or more acoustic components aligned in different directions and electrically connected together in parallel. The phase slope of the acoustic components are similar but their temperature coefficients of delay are different whereby their resultant frequency response is compensated over a useful temperature range. The acoustic components may be delay line employing surface waves or surface skimming bulk waves, or one or two port resonators using surface waves.

Abstract: A novel liquid crystal compound has the molecular structure: ##STR1## where R is an alkyl group, which may contain up to 18 carbon atoms and which may be normal or branched and may contain a chiral center, ##STR2## is a bicyclo (2.2.2) octane ring, --X-- is and Y is a cyano group CN or R.sup.1 or OR.sup.1 where R.sup.1 has the same definition as R.The compound may be used in mixtures with other liquid crystal compounds in the same or other families and the compound or mixtures may be used in known liquid crystal devices, eg the twisted nematic and cholesteric-to-nematic phase change devices, depending on its properties.

Abstract: A liquid crystal compound having the formula: ##STR1## where X is --CH.sub.2.CH.sub.2 -- or CH.sub.2 OY is ##STR2## and R is a straight or branched (possibly chiral) alkyl group having up to 15 carbon atoms.

Abstract: Apparatus for degrading safety fuel of the type containing an anti-misting polymer and comprising a bank of interfitting stators and rotors with a plenum chamber at some station along the bank, whereby rotation of the rotors will cause safety fuel pumped through the apparatus to be subjected to sufficient shear and local acceleration to be degraded to a state acceptable for engines and their control apparatus.