Abstract: The thermal hysteresis of quartz crystal resonators is measured by exciting two modes of a quartz crystal of interest with an external frequency source at a preselected temperature, calculating the difference frequency as between the modes, resetting to the original set temperature after temporarily altering the temperature, remeasuring the frequencies while maintaining the temperature and the difference frequency at the same respective values as the original values, and taking the mode frequency difference as representative of the thermal hysteresis of the crystal.

Abstract: A circuit is shown for representing the internal temperature of a crystal, through a combination of certain harmonic frequencies excited in that crystal. By forming a signal which is equal to nF.sub.A -F.sub.B, i.e., n times a lower harmonic frequency minus F.sub.B, an nth harmonic frequency, or F.sub.A -1/n F.sub.B, e.g., it is possible to have a signal which is near linearly dependent upon temperature which can be used in representing same. This composite signal is also seen to be highly sensitive to temperature changes yielding an improved thermometric system as compared to conventional systems.

Abstract: A multi-terminal Group III-V semiconductor high electron mobility field effect transistor comprised of a sandwich of molecular beam epitaxially grown layers and including two high mobility charge flow channels in respective two dimensional electron gas regions implemented, for example, by at least one doped layer of aluminum gallium arsenide adjacent an undoped gallium arsenide layer separated by a heterojunction. A pair of opposing two dimensional electron gas (2DEG) regions are generated in the layer of undoped gallium arsenide by the bending of the energy levels of the semiconductor materials. Charge flow occurs in a unidirectional fashion from one channel to the other in the common undoped gallium arsenide layer under the control of an electric field applied transversely through the structure by means of a top gate electrode and a bottom field plate electrode.

Abstract: A bakeable evacuative fabrication assembly for the production of permanent agnets formed by assembling discrete magnetic elements on a core, enclosing such assembly in a close-fitting container, providing end closures on said container, and providing a one of said end closures with a sealably closeable cold mold vent means.

Abstract: Phased array antennas are rapidly tested for performance degradation utilng a beam steering computer unit and built-in test equipment. The antenna includes a plurality of bays in a planar matrix, each bay having subarray modules containing pairs of dipoles. The beam steering unit controls scanning of driver cards having drivers which apply bias voltages to phase shifter diodes or bits of various fixed angular sizes in a main array and subarray. The bits are sequentially tested for current faults, with information obtained on number, size, and location of failed bits determining performance degradation of a predetermined threshold. Larger phase bits of the main array are given more weight than smaller subarray bits. The effect of the failures on sum beam gain and azimuth and elevation differences pattern null depths are computed and compared with the threshold to indicate whether performance is acceptable.

Abstract: Permanent magnet structures in several alternative forms are fabricated f multiplicities of permanent magnet segments of magnetic materials, preferably rare earth compounds, with the segments displaced radially from each other progressively along the structures elongate axes so as to produce a heliform magnetic field extending centrally in a passage through the structure.

Abstract: The digital frequency divider (or synthesizer) produces non-integral submultiples of an input frequency by alternately dividing its input by two integers by means of two integral digital frequency dividers, one of which produces an output higher than the desired non-integral submultiple and the other of which produces an output lower than the desired non-integral submultiple. The desired non-integral submultiple is obtained by alternately switching the circuit output to two integral digital dividers, the duty cycle of the switch determines the precise output frequency obtained. The concept can be implemented with programmable digital counters and logic circuitry. The circuitry can be used to implement a novel method of duplicating an accurate signal with improved stability. A circuit useful in practicing the method measures the ratio of two frequencies.

Abstract: A magnetic device of permanent magnet materials for the control of linearly xtending annular cross-sectioned magnetic fields formed of two concentrically nesting magnetic tubular elements defining an annular space therebetween, and inner and outer cladding magnets radially disposed around the outer of said tubular elements and interiorly of the inner of said tubular elements, the cladding magnets being thicker at the end extremities and diminishing in thickness towards and to the plane of zero magnetic potential at or near the center line of the device measured along its longitudinal axis.

Abstract: Selective etching of microelectronic devices comprising crystal substrates s achieved by electrically masking conductive areas thereon which are not to be etched by ionic bombardment. The electrical masking is accomplished by biasing the selected areas with a bias voltage which will repel the ions, which are attracted to all of the unbiased portions of the microelectronic device.

Abstract: A rare earth permanent magnetic apparatus for the containment and control thout any substantial loss of field flux comprising electro-deposited layers of rare earth magnetic material disposed and laid up around a ferrite center core element, the first or inner layer comprising a uniformly thick supply magnet to produce the magnetic field to be controlled, and the second or cladding magnet constituting a layer of diminishing thickness from the outboard ends of the device towards and to the plane of zero magnetic potential at or near the middle of the device.

Abstract: Steerable phased array antennas of the tapered type in which the antenna ment power is maximum at the center of the array and tapers off on either side thereof. The phase shifters of each antenna element are of the binary digital type with the number of stages and hence the phase accuracy being maximum for the high power center antenna elements and tapering off on either side thereof. Redundant stages for the binary phase shifters can be provided to increase reliability.

Abstract: Acoustic signal processing apparatus for the frequency-partition processing f a wideband RF spectrum surface acoustic wave (SAW) input signal into a multiplicity of relatively narrowband individual contiguous acoustic wave output signals, utilizing a wideband, linearly-dispersive, slanted array input transducer arranged on a wave-conductive surface with multiple arrayed output transducers, each frequency-responsive to a respective band of frequencies emanated from the input transducer.

Abstract: A millimeter wave microstrip transmission line is coupled to a solid state echanically tunable cylindrical resonating coaxial cavity millimeter-wave oscillator by means of a probe extending linearly from the microstrip through an access slot in the cylindrical cavity wall into the zone of optimum electric field strength in the oscillator cavity to effect the translation of a TEM wave from the resonating cavity to the microstrip line at optimum power transfer and without wave mode change.

Abstract: A plurality of contiguous cavity pairs of multipactor input and output cavities respectively formed in two opposing ridge waveguide sections and which are mutually separated by an acceleration drift region of relatively high DC electric field strength. Both waveguide sections include means such as an RF window at one end for coupling RF power in and out of the sections while the other end is suitably terminated and additionally provides the structure which can be placed under a vacuum to properly function. The cavity pairs are arranged in a linear array subassembly within each of the waveguides and are designed to have a broadband frequency response by progressively increasing in frequency so that half power points of contiguous cavity pairs are in close proximity.

Abstract: Silicon wafers are imprinted with microelectronic circuit patterns by first ithographing the outlines or peripheries of all circuit features of a given wafer level by means of a narrow line formed by direct-writing electron beam lithography utilizing a positive electron resist, then using proximity photoprinting to complete the lithography of that level using a positive photoresist and a photomask with oversized opaque areas so that the pattern edges on the wafer exposed to the flux passing through the photomask will fall within the peripheral lines formed by the electron beam.

Abstract: An electro-optical interface unit is shown for interfacing an all-optical telephone to a conventional electrical-metallic-type telephone communications system, having conventional electrical subscriber units, switching, and supervisory systems. An overall all-optical telephone communication system, of which an all-optical telephone is a part, is envisioned. The disclosed system makes use of optical-acoustic-electrical types of transducer elements, light modulators, and optical junctions, among other novel elements.

Abstract: An apparatus and a method which permits a plurality of master stations to be attached to a communications channel and to provide an arbitrating mechanism within each master by which one master station is designated as in control of the communications channel. The method overcomes the single point failure of the true master slave station by providing redundant masters. Furthermore, each station in the network is polled by a grant transmission at a constant interval of time irrespective of which master is in control of the bus to assure efficient utilization of the bus.

Abstract: An electronic varactor tuner is integrally combined with a mechanically tuned Gunn oscillator to provide an increased tuning range in a light weight, compact, rugged combination with easily and quickly replaceable components.

Abstract: A millimeter wavelength oscillator combining a mechanically tunable resonating cavity oscillator element with an electronically tunable solid state diode element provides a basic stable steady wave energy source with fine-tuning capabilities not possible with a resonating cavity oscillator alone, and with an apparatus structure which is light in weight, compact, mechanically sturdy, and with easily accessible and quickly replaceable component parts.

Abstract: An integrated circuit tunable cavity oscillator for extremely high freque operation in image line waveguide. The oscillator includes a metal base with a cylindrical bore, a dielectric or semiconductor waveguide mounted atop the metal base and having a bore which is continuous with the metal base bore. A Gunn or IMPATT diode is assembled in the metal base bore on top of a drum which is urged upwards toward the waveguide bore by a spring located behind the drum. From above, cavity tuning means including a top disk and a threaded screw cover the waveguide bore and push the diode into the metal base bore to define the cavity height of the coaxial cavity of the oscillator. The waveform, which is set up in the recessed cavity in the metal base, is launched into the waveguide. Thus, a ruggedized, low cost, tunable (by a tuning screw) and low weight oscillator for millimeter wave image line or microstrip operation is obtained. Furthermore, the oscillator diode and cavity defining hardware are easily replaceable.