Abstract: A hearing aid or audio communication system includes an earpiece (10) that can be hidden in the ear canal, and which communicates wirelessly with a remote processor unit, or RPU (16), that enhances audio signals and can be concealed under clothing. Sounds from the environment are picked up by a microphone (12) in the earpiece and sent with other information over a two-way wireless link (17) to the RPU (16). The wireless link (17) uses microwaves for component miniaturization. Furthermore, use of radar technology to implement the wireless link (17), with an RPU (16) interrogator and earpiece (10) transponder, reduces earpiece size and power, as no microwave oscillator is needed in the earpiece (10). Optional secondary wireless link circuitry (19) can be used between the RPU (16) and a cellular telephone system or other sources of information. Electronic voice recognition and response can control system operation.

Abstract: A crossed-field amplifier tube is constructed in which there is substantially no direct RF coupling between the output of the slow-wave structure on the anode and the input of the slow-wave structure of the cathode to thereby obtain a cathode-driven tube which is capable of RF pulsed operation into a linear accelerator cavity which presents a mismatched load, a short circuit impedance, at initiation and termination of the RF pulse without breaking into oscillation. During the RF pulse, the tube operates into a substantially matched load and provides high peak and average power.

Abstract: A crossed-field amplifier circuit of the type using a CFA tube with a slow-wave structure for the anode and the cathode, each with an input and an output terminal, and a magnetic field in the axial direction, and signals of the same frequency from a common source and of controlled phase difference and amplitude applied to the input terminals of the anode and cathode slow-wave structures whose fringing fields interact with the electron cloud between the anode and the cathode to form well defined cloud fingers which result in amplification of the input signals to provide at the output terminal of the anode an amplified signal having lower random noise than hitherto available from CFA amplifiers.

Abstract: A flextensional electroacoustic transducer with end plates and outwardly convex shells connected to form a housing containing a transduction drive member and laterally disposed tensioning members in contact with said end plates. The tensioning members are connected by hinges allowing rotational oscillatory movement of the end plates with respect to said hinges. Another embodiment includes end plate hinges where the end plates contact the transduction drive member and hinges where the shells connect to the end plates.

Abstract: Slow-wave structures are formed by the method of this invention in the form of helical or coupled-cavity structures. A helical waveguide form of slow-wave structure is formed of a solid rod of copper machined with a deep, narrow helical groove. A copper sleeve is brazed to the periphery of the resulting helical thread to form a helically spiraling pathway about a solid axially centered and axially extending center portion. The center portion is then totally eroded away to form a slow wave structure having a helical radially-extending portion, or if only partially eroded with an inner helical axially-extending ridge to provide a helical axially-centered gap between adjacent ridges. The helix is extended into a rectangular waveguide for coupling the slow-wave structure to the source and to the load. The coupled-cavity forms of waveguide slow-wave structures are formed by machining disks from a solid rod of copper.

Abstract: A beam is directed to an interfering source to obtain the best estimate of this signal. The beamformer output is fed into an inverse beamformer in such a way that the total delay experienced by a signal from any element of the array is the same as that of other elements in the array. Each output from the inverse beamformer is a spatially filtered replica of the signal received by the corresponding array element except for a fixed time delay constant for each element. The same delay is imparted in a second channel to each of the array outputs which are substituted from the corresponding inverse beamformer outputs. If the amplitude and delay of each signal to the subtracter are equal, the outputs from each of the subtracters will no longer contain signal components from the direction of the interfering signal.

Abstract: The drive modules of a magnetostrictive transducer are fabricated from interleaved permanent magnet disks (samarium cobalt) and high-strain, low-permeability magnetostrictive lanthanide alloy (Terfenol-D) disks to form a stack of such interleaved materials of substantially uniform magnetic field distribution in the stack. Two such stacks in side-by-side relationship provide a series-aiding magnetic circuit completed through high-permeability flux return pole pieces at their ends thereby providing a substantially uniform magnetic field distribution in the stack. Each stack has longitudinally-extending and electrically-insulated planar cuts and each flux return pole piece is a laminate of thin sheets of high-permeability electrically-insulated steel to reduce eddy current losses resulting from the AC field. The steel sheets are constrained by a nonmagnetic end-block into which the steel sheets are inserted and bonded.

Abstract: A locking type of connector assembly consists of two connector halves, one half having a more compliant surface in pressure contact with a surface of the other half. The surfaces have mating protrusions and recesses which are in pressure contact. The torque required to misalign the mating surfaces after tightening the connector is sufficiently great to prevent loosening of the connector by vibration.

Abstract: A receiver for active sonar systems comprises two fundamentally different detection processes operating simultaneously with the output of each detection process being combined by a computer utilizing a computer-aided detection algorithm. One detection processor is a segmented replica correlator (SRC) and the other detection processor is a polarity coincidence correlator (PCC). Each detection processor provides to the active computer-aided detection algorithm a list of ranges and bearings of a relatively small number of detection events. The computer algorithm operates on these events to compare events from the current ping and the previous ping for each of the processors.

Abstract: A seismic energy source provides a bias pressure and oscillating pressure force on a piston mounted transversely to the major axis of the well bore and in pressure contact with the wall of the well bore. A seismographic energy wave is generated in the surrounding earth by oscillating the pressure of the piston against the well wall. This apparatus uses the pressure of ambient fluid in the well bore to reduce the power required to provide pressure contact and to oscillate the piston against the wall.

Abstract: Slow-wave structures are formed by the method of this invention in the form of helical or coupled-cavity structures. A helical waveguide form of slow-wave structure is formed of a solid rod of copper machined with a deep, narrow helical groove. A copper sleeve is brazed to the periphery of the resulting helical thread to form a helically spiraling pathway about a solid axially centered and axially extending center portion. The center portion is then totally eroded away to form a slow wave structure having a helical radially-extending portion, or if only partially eroded with an inner helical axially-extending ridge to provide a helical axially-centered gap between adjacent ridges. The coupled-cavity forms of waveguide slow-wave structures are formed by machining disks from a solid rod of copper. The disks are supported in their desired positions by an axial retained portion of the rod until the disks are brazed inside a cylindrical shell of copper.

Abstract: A piezoelectric polymer (PVDF) hydrophone array consists of multiple layers disposed symmetrically about a stiffener layer. The stiffener layer prevents flexural modes in the operating frequency band and provides a mounting structure for acceleration noise cancellation. The piezoelectric polymer layers are attached to the stiffener layer either directly or through intervening layers which provide mechanical vibration isolation of the polymer and stiffener layers.

Abstract: A cylindrical array employs rectangular planar array segments which extend in the axial direction when assembled on a cylindrical conducting plate having flat longitudinal portions to which the planar array segments are attached. Each planar array segment comprises two columns of planar transducer elements with each column extending in the axial direction of the cylinder. The acoustic center of each transducer lies on the circumference of a right circular cylinder. The acoustical requirements of a cylindrical array are satisfied to allow multiple beams to be formed with a minimum of complexity and with the same versatility as in the curved array segment cylindrical array embodiment.

Abstract: A waveguide helical slow-wave structure is formed of a solid rod of copper machined with a deep, narrow helical groove. A copper sleeve is brazed to the periphery of the resulting helical thread to form a helically spiraling pathway about a solid axially centered and axially extending center portion. The center portion is then partially eroded away to form a slow wave structure having a helical radially-extending portion with an inner helical axially-extending ridge to provide a helical axially-centered gap between adjacent ridges. The slow wave structure contains the microwave energy which follows the spiral path of the structure and produces RF voltage across the gap of adjacent portions of the ridges to thereby form a gapped-wall surrounding an axially-extending hole for gap electric field interaction with the axial electron beam of a traveling wave tube of which the slow wave structure is a part.

Abstract: A crossed-field amplifier has a cathode in the form of a P-N junction semiconductor which is biased to the conductive state to cause the crossed-field amplifier to amplify. The P and N regions of the semiconductor are connected to an energy source which is pulsed to produce conduction in the P-N junction and thereby allow secondary emission from the cathode. A reverse bias voltage prevents secondary emission from the cathode. The tube requires only low voltages to be applied to the cathode P-N junction to completely deactivate the crossed-field amplifier tube without requiring the removal of the RF drive pulse applied to the cathode- or anode-slow-wave circuit and without requiring the removal of the DC high voltage power supply which therefore need not be pulsed.

Abstract: A stacking ring of elastomeric material for supporting a plurality of fairings is formed by molding the elastomeric material around a cable which has been prepared with a bonding agent to provide a compliant ring capable of supporting substantial loading along the cable axis. Low-friction bearing surfaces may be incorporated in the ends of the ring which also increase the axial force retention capability of the ring.

Abstract: A crossed-field amplifier comprises a cylindrical array of anode circuits for broad-band high-power crossed-field operation at millimeter waves. The electric field between the cylindrical anode and the surrounding cylindrical cathode is radial and the magnetic field is axial in the space between the anode and cathode. This space is the interaction region where the power is uniformly distributed over the circumference of each cylindrical array. Power flows radially in and out of the elements of the anode circuit and also axially along the cylindrical TE.sub.01 guide within the cylindrical anode. The guide is equipped with damping elements for mode control and filter elements for controlling the overall gain, bandwidth, and stability. Because of the radial flow and axial flow of power in the amplifier, it has been termed a Radaxtron.

Abstract: The composite transducer of this invention comprises a prior art longitudinal vibrator-type transducer for transmission of energy and a piezoelectric polymer hydrophone attached to the radiating face of the transducer for the receiving function. During transmission the receiver transducer is short-circuited, and during reception the transmitter transducer is terminated in an electrical impedance that optimizes receiver response and minimizes transducer self-noise. The frequency response of the polymer hydrophone is relatively flat and extends over a much greater frequency range than the transducer.

Abstract: A transducer which uses paramagnetic magnetostrictive rods or bars, e.g., compositions of the lanthanide series of elements such as Tb.sub.0.3 Dy.sub.0.7 Fe.sub.2, has the bars biased with a lengthwise flux by a permanent magnet, e.g. samarium-colbalt, of high resistance to demagnetization by the alternating field applied to the bars by alternating current in a coil surrounding the bar. The magnet is outside the coil to reduce the ac field to which it is subjected. Uniformity of flux density along the length of the bars is enhanced by having adjacent ends of the bars subjected to like-polarity poles of the permanent magnets associated with each bar.

Abstract: Sonar ice thickness measurement comprises transmitting an AM and subsequent CW sonic radiant energy signals from the water toward the sonic signal reflecting ice cap. Reflection of the CW signal from the water-ice interface and reflection from the water-air interface of the modulating frequency, generated by non-linear or parametric effects in the water by the modulated transmit signal, causes the CW signal to be modulated to generate side bands at the modulating frequency on each side of the carrier frequency to provide an FM high frequency signal. Detection of the FM signal determines the time of arrival of the echo of said detected FM signal relative to the detection of the reflected modulated signal from the water-ice interface.