Abstract: This invention teaches how to reduce the copper content of a commercially available, all-copper, double-wall-vented, coil & tube Gravity Film Heat Exchangers (“GFX”) developed for the GFX™ system of U.S. Pat. No. 4,619,311. For example, a GFX+™ equivalent of a residential Model G3-60 GFX can be made using 71% less copper. Such significant copper-savings, with comparable heat transfer coefficient (“U”), effectiveness and coil pressure drop, is achieved by improvements in innovations disclosed in Provisional Patent Application 60/709,889 (Filing date: Aug. 22, 2005). Unlike conventional, single and multi-coil GFX's currently produced by several manufacturers, the present invention enables the use of a variety of metal and/or plastic components to achieve either single or vented-double-wall construction and lower manufacturing costs. In fact, higher U-values can be achieved by increasing the potable-water pressure drop of a GFX+ equivalent of any coil & tube GFX.

Abstract: Prior art arrays of TR modules suffer from the disadvantage of requiring heavy and bulky waveguides or coaxial cables to provide controls therefore. In the present system, by using incoherent light to coherently synchronize the different TR modules of the array to produce a coherent phase array, the bulky waveguides and coaxial cables no longer are needed. To provide for the coherent synchronization of the phase array, oscillator and control signals are multiplexed onto different incoherent optical signals. The multiplexed optical signals are then summed and sent, via an optical fiber, to the TR modules of the array. At each of the TR modules, the oscillator signal and a corresponding control signal are separated from the summed optical signal and are used to weight the phase and amplitude of the radar signal to be transmitted from the TR module. When the properly synchronized and weighted modulated radar signal is sent from each of the TR modules, a coherently synchronized radar signal is produced.

Abstract: Prior art single FET switches suffer the disadvantage of uncertainties in the turning on and off thereof due to the high back bias voltage required. In the present system, by using a dual FET configuration, with the respective source regions of the FETs connected at a common node and a floating bias voltage source connecting the common node to the respective gate regions of the dual FET, a switching circuit which is capable of handling higher voltages and whose dB compression stays constant is provided. Since the dual FET circuit is symmetrical, depending on the polarity of the biasing voltage, the drain and the source regions are interchangeable.

Abstract: To eliminate bulkiness associated with the conventional transmission of control signals to a phase array, and to overcome the precise requirements needed to coherently control a phase array in the prior art, the present invention uses incoherent light to provide optical synchronization of the phase array. For the system of the present invention, incoherent light, in the form of different optical signals having multiplexed thereon a local oscillator signal and a command signal including a plurality of control signals, are summed by a wavelength division multiplexer and sent, over an air path, to each TR module of the phase array. On receipt, each TR array separates from the summed optical signal the oscillator signal and a control signal which is recognizable and to be used only by that TR module. The separated oscillator signal is next fed to a mixer, for modulating a radar signal.

Abstract: An adaptive power limiter circuit for suppressing power spikes output by a receiver to reduce the chances of damage to the receiver includes a first attenuating stage having an input terminal for receiving power spikes of input magnitude. A first FET is coupled to the input terminal and an output terminal is coupled to the first FET for providing power spikes of output magnitude which are diminished in power relative to the input magnitude. A second attenuating stage has an input terminal connected to the output terminal of the first attenuating stage for receiving the power spikes output by the first stage, an additional FET is coupled to the input terminal of the second stage and a second stage output terminal is coupled to the additional FET for providing power spikes of output magnitude which are considerably diminished in power relative to the input magnitude of the spikes at the input terminal of the first stage.

Abstract: To eliminate the complexity and the weight involved in the use of a Butler matrix, the present invention matrix antenna array uses a combination of processors and analog multipliers for weighting the signals, either to be transmitted or received, from the corresponding antenna element of the array. Since the analog multipliers are adaptable to operate in the microwave frequency, the control signals can be multiplied with the radar signal directly so that complexity of construction, bulkiness and heavy weight are eliminated from the matrix antenna array of the present invention.

Abstract: The parasitic capacitance which is inherent in an amplifier stage fabricated by MMIC or MIC technology oftentimes is cumbersome and of little use. The present invention utilizes this parasitic capacitance for effecting a quadrature circuit, fabricated onto the same substrate as the amplifiers for matching and biasing the amplifiers, thereby providing for broadband operation. When a pair of amplifiers are driven in quadrature, there results a low Q, low inductance circuit which has enhanced efficiency and operates at a decreased temperature.

Abstract: In a conventional mixer circuit, in order to have high conversion gain, high input power is needed. For the mixer circuit of the present invention, by incorporating a modified cascode circuit whereby the input stage FET has a higher saturation current than the output stage FET, the same high conversion gain can be achieved. In addition, the present invention mixer circuit requires an input DC power that is considerably less than that needed for the conventional mixer circuit.

Abstract: A new type of high voltage FET circuit has been developed which offers a dramatic improvement in performance as compared to a common source amplifier stage. The new circuit offers inherent performance advantages in both MIC and MMIC power amplifiers. To achieve this end, the FET circuit has a common source FET connected to a common gate FET, with the common source FET having a width substantially greater than that of the common gate FET such that the common source FET does not saturate even when the common gate FET is turned fully on. To provide biasing for the circuit such that its breakdown voltage can be substantially increased, a RC circuit including a connected in parallel diode is used.

Abstract: Conventional cascode circuits achieve a performance which is not optimum. To enhance performance, the cascode circuit of the present invention has an input stage FET that has a saturation current which is greater than the saturation current of the output stage common gate FET. Since the maximum power of a cascode circuit is related to the maximum voltage swing at the drain of the common gate FET, when the saturation current of the common source FET is greater than that of the common gate FET, the common source FET essentially acts as a switch to turn the common gate FET fully on, without dissipating any appreciable voltage from the same, so that a maximum voltage swing may be produced at the drain of the common gate FET.

Abstract: A transistor circuit is provided with a symmetrical floating configuration for attaining multifunction operation of a transistor having symmetrical source and drain characteristics, preferably a GaAs MESFET. The circuit includes a balun which may be configured as a transformer, a differential amplifier, or a magic-tee waveguide depending on the frequency of signals to be processed by the circuit. Balanced terminals of the balun may be directly or capacitively coupled to source and drain terminals of the transistor. Tuning circuits are employed for applying signals having different frequencies to the transistor and for extracting intermodulation products generated by the transistor in response to the signals at the different frequencies. With the direct connection between the balun and the transistor, alternating voltages may be impressed between the terminals of the transistor to alternate source and drain regions of the transistor.

Abstract: A system for recovery systems improving heat recovery from hot waste water is provided whereby cold feed water is preheated by means of extracting heat from hot waste water by passing said hot waste water and said cold feed water through a heat exchanger. Said preheated feed water is directed simultaneously to the hot water heater and to mixing valves at the point of usage of tepid water. Equal volumes of waste water and cold feed water flow through the system.

Abstract: A delay line circuit provides variable delay and phase shift to electric signals propagating along the delay circuit. The circuit is formed of a set of varactors constructed either as varactor chips or as a set of mesas upstanding from a gallium arsenide substrate. A ground plane interconnects bottom terminals of the varactor chips while a strip line conductor interconnects top terminals of the varactor chips. In the case of the mesa configuration, a metallized layer covers the regions between the mesas without contacting the base portions of the mesas. The strip line conductor makes contact with the respective mesas via a set of metallic posts upstanding from respective ones of the mesas. Dielectric material may be inserted between the strip line conductor and the metallic layer to position the strip line conductor relative to the metallic layer, which layer serves as a ground plane in a transmission line comprising the strip line conductor.

Abstract: An electromagnetic transducer for exciting selected modes of ultrasonic vibration in a tubular body. The transducer includes a plurality of rows of permanent magnets of alternating polarity with a coil provided about the magnets whereby a current is conducted through the magnetic fields. The rows of magnets are provided in carriers which are yieldably biased towards the inner surface of a tubular body during inspection.

Abstract: Disclosed is a correlation receiver for processing an elctrical signal derived from an acoustic signal in a test object, including a signal generator for producing a reference waveform, a multiplier for combining the electrical signal and the reference waveform, an inegrator for integrating the combined signal, and a sample and hold circuit for detecting and holding the output of the integrator. In another embodiment, the signal generator also produces a second reference waveform in quadrature with the first reference waveform, and the receiver further inclues a second multiplier for combining the electrical signal and the second reference waveform, a second integrator for integrating the combined signal, and a means for combining the integrated first and second combined signals to produce an output indicating the structural integrity of the test object.

Abstract: Disclosed is a method for determining the thickness of an object, including the steps of generating a higher order mode ultrasonic wave at a first location on the object, varying the frequency of the generated wave, and measuring, at a second location on the object, the minimum frequency at which the generated wave will propagate in the object. Where the ultrasonic wave generated is a horizontally polarized shear wave, the thickness t may be calculated from the relationshipt=(n V.sub.s)/(2 f.sub.c),where:n is the wave mode number,V.sub.s is the shear wave velocity, andf.sub.c is the minimum propagation frequency.Alternatively, the steps may be repeated for the next consecutive frequency minimum and the thickness t calculated from the formulat=V.sub.s /(2 .DELTA.f.sub.c)where: .DELTA.f.sub.c is the difference between two consecutive frequency minima.

Abstract: Disclosed is a method for evaluating the structural integrity of an object, including the steps of generating a lowest order horizontal shear wave in the object, detecting the wave after it has propagated through the object, time gating the detected signal to reject nonuseful portions, Fourier transforming the time response of the detected signal into a frequency dependent response, and predicting the structural integrity of the object from the characteristics of the frequency response.

Abstract: Disclosed is an electromagnetic acoustic transducer, including a source of magnetic flux for establishing a static magnetic field, an electrical conductor for conducting an alternating current in the static magnetic field, and an electrically conductive, nonmagnetic shield disposed between the source of magnetic flux and the conductor.

Abstract: Disclosed is a nondestructive test device for detecting a flaw proximate to a welded seam in a pipe, including an electromagnetic acoustic transmitting transducer for generating a horizontally polarized shear wave in the wall of the pipe, a high frequency generator operatively connected to the transmitting transducer for energizing the transducer, an electromagnetic acoustic receiving transducer for responding to a horizontally polarized shear wave within the wall, an amplifier operatively connected to the receiving transducer for boosting the response signal of the transducer, and an indicating instrument for receiving and displaying the amplified response signal. In the test method disclosed, a horizontally polarized shear wave is generated in the wall, the pipe is monitored to detect a reflected horizontally polarized shear wave, and a time-dependent representation of the amplitude of the reflected wave is displayed.

Abstract: Disclosed is a method for evaluating a discontinuity in an object. As used to measure the depth of a surface discontinuity in a plate type of object, the method includes the steps of generating a horizontally polarized shear wave in the object directed substantially along the axis of the discontinuity, passing the generated wave through an aperture to diffract the wave prior to its arrival at the discontinuity, detecting the wave after it has propagated through the discontinuity, and calculating the depth of the discontinuity by correlating the phase and amplitude of the detected wave to the phase and amplitude of a similar wave propagated in a region of the object which is free of discontinuities.