Abstract: A tubular structure having a transverse magnetic field that varies in eit the longitudinal direction or the lateral direction. In one embodiment, a permanent magnet tubular structure has a working magnetic field space that is partially bounded by pole pieces that reduce the height of the working magnetic field space. A laterally varying magnetic field is formed within the tubular structure. In another embodiment, a permanent magnet tubular structure is comprised of sections made of a permanent magnetic material, each section having a different remanence. The adjacent sections, having different remanence, form a linear array resulting in a longitudinally varying magnetic field gradient within the working space. The present invention has many practical applications such as in magnetic resonance imaging.

Abstract: A pair of hollow permanent magnets mounted to form a toroidal stator having cylindrical gaps and opposed cavities. The magnets are polarized such that their magnetic flux passes in one direction through the gaps to intersect the rotor along two cylindrical bands and then passes through the magnetic shell and subsequently in the opposite direction through the cavities to intersect the rotor in a cylindrical region located between the cylindrical bands. An electrical circuit couples a utilization device to the rotor. Another embodiment of the invention uses a magnetic mirror to replace one of the permanent magnets. Still other embodiments teach the use of a plurality of toroidal stators mounted in tandem about a common rotor. The machine may be used as a homopolar generator or a homopolar motor.

Abstract: A planar tunable YIG filter assembly comprising a first substrate having on one side thereof spaced ridges, a first conductor spaced from and between the ridges, a dielectric spacer and YIG disk is mounted on said spacer whereby, a bandpass filter is established between said first conductor and a second conductor that is orthogonal with said first conductor and on a second substrate that is in contact with the ridges when means are provided for producing a magnetic field that is perpendicular to the substrate in the area of intersection of the first and second conductors.

Abstract: A remote temperature sensor includes a microwave oscillator which generates n output signal having a frequency which is proportional to the temperature of the environment in which it is located. The oscillator includes a relatively high transition temperature superconducting (HTSC) ring coupled to a transistor in a plurality of microstrip line oscillator configurations including those of a reaction oscillator, a transmission oscillator, a reflection oscillator and a parallel feedback oscillator. The superconducting ring operates below its transition temperature and in so doing, acts as a high Q resonator whose resonant frequency is proportional to temperature.

Abstract: An electrical machine having a stator formed from a pair of cup-shaped permanent magnets symmetrically disposed on opposite sides of a conductive, disk-shaped rotor. The magnets are polarized such that a portion of their external magnetic flux passes in one direction through a short peripheral gap formed by the magnets in which the periphery of the rotor is disposed. The remainder of the external magnetic flux substantially passes in the opposite direction through a cavity defined by the inner volume of the cup-shaped magnets. The inner portion of the disk-shaped rotor is disposed in this cavity. One embodiment of the invention implements the cup-shaped magnets with modified "magic spheres" mounted on either side of the conductive disk-shaped rotor. Other embodiments use a magnetic plate on one side of the disk-shaped rotor to act as a magnetic mirror for a cup-shaped magnet mounted on the other side of the rotor.

Abstract: A planar stripline type of ferroelectric phase shifter which includes a set f series coupled phase shifter sections, each having mutually different and binary weighted lengths of ferroelectric phase shifting material. Fixed amplitude control voltages are respectively applied to one or more lengths of ferroelectric material the permittivity and effective electrical length of which change to provide a desired composite phase shift. The phase shifter, moreover, employs half wavelength spacings between elements or matching networks therebetween so that the microwave signal propagating through the phase shift will be minimally impeded between the input end and an output end.

Abstract: The present invention utilizes the internal photovoltaic effect of a GaAs SFET to mix an RF modulated optical signal with a microwave signal. As those skilled in the art will readily recognize, a GaAs MESFET generically comprises an n layer of GaAs (channel) deposited on semi-insulating GaAs (substrate). Source, gate and drain electrodes are then formed on the channel with the gate acting as a Schottky barrier. In this standard MESFET, the difference in doping between the channel and substrate produces a potential barrier. It has been found that when the device is illuminated, the potential barrier is reduced in the region between the source and the gate and drain and the gate. This reduced potential barrier allows more drain current to flow from the device. It has been found that this drain current photoresponse is highly non-linear with respect the gate voltage applied to the device and therefore, it may be used to mix RF modulated optical signals with microwave signals.

Abstract: The electrical breakdown strength of capacitors is increased by briefly esing the dielectric, the metal foil, and/or the fully assembled capacitor to a low pressure, low temperature gas plasma.

Abstract: A fundamental or subharmonic optically injection locked oscillator is coupled to a phase locked loop circuit. The injection locked oscillator has two single stage HEMT amplifiers with parallel feedback from the drain of a second transistor to a gate of a first transistor. A feedback resonant network controls the oscillator frequency. A microwave/millimeter wave source modulates a laser diode and the signal from the laser diode is then transmitted via an optical fiber to a PIN photodetector diode. The signal from the photodetector diode is injected into the oscillator at an nth subharmonic of the oscillator frequency. The feedback network may consist of a microstrip gap resonator with two tuning varactors at the ends of the resonator. The phase locked loop includes a balanced mixer used as a phase detector to compare the nth harmonic of the signal from the photodetector diode to the sampled output of the oscillator.

Abstract: This disclosure relates to a circuit for detecting the phase transitions in a PSK signal in the presence of a stronger CW signal. A SAW transform circuit carries out "piecewise" Chirp-Z transformations of the PSK and CW signals so as to achieve a separation of the same in the time domain. A gate and a pulse width discriminator are both coupled to the output of the Chirp-Z transform circuit. The discriminator rejects all signals except the transformed phase transitions of the PSK signal. The output of the discriminator is utilized to periodically enable the gate for short durations (e.g., 2nsec.) to selectively pass the transformed PSK signal including transformed phase transitions thereof. The gated output is delivered to a dual channel SAW differential delay line whose two channels are of different lengths to provide a predetermined amount of delay (t) therebetween (t.ltoreq.PSK bit duration).

Abstract: The present invention comprises a semi-insulating layer of GaAs with p+ and layers of aluminum gallium arsenide AlGaAs grown on one side of the semi-insulating GaAs and with p and n+ layers of AlGaAs grown on the other side of the semi-insulating GaAs. Ohmic contacts are grown on both sides of the thyristor as well as low temperature GaAs to provide for surface passivity.

Abstract: A Circular Polarization Selective Surface (CPSS) for circular polarized electromagnetic waves is formed from a number of resonating elements arranged in a plane. This type of surface may be used in a wide range of reflector antennas. Each resonating element is formed from a number of electrically conductive segments connected end-to-end one to the other with each segment having a predetermined length and having a total approximate length of 1.lambda.. A central segment having a length about 1/4.lambda. determines the resonant frequency for the element. This central segment extends parallel to the z-axis of a right-hand set of three mutually perpendicular axes x, y and z wherein the circular polarized electromagnetic wave is directed along the z-axis. A second segment is connected to one end of the central segment and extends parallel to the x-axis with a third segment being connected to the other end of the central segment extending parallel to the y-axis.

Abstract: The combination of a photoconductive switch coupled to an energy storage ice wherein the switch is comprised of photoconductive semiconductor switch while the energy storage device comprises a tapered radio transmission line. A photoconductive semiconductor gallium arsenide switch is embedded in a circular disc of dielectric material having a thickness dimension which reduces linearly outward from the center, with upper and lower layers of continuous radial metallization configured in a circular pattern located thereon. The upper layer of metallization includes an apertured grid adjacent one surface of the switch, while the outer conductor of a coaxial output signal line is connected to the metallization layer on the opposite side with the inner conductor thereof passing through the dielectric layer to the undersurface of the semiconductor switch.

Abstract: Bulk gallium arsenide having a high hold-off voltage is optically activated by a laser resulting in high power output. A high voltage input is applied to a semi-insulating gallium arsenide material. The gallium arsenide material is activated by laser light, thereby resulting in large current conduction. An external oscillating signal is superimposed on the high current resulting in a high power output.

Abstract: An image detecting device is disclosed wherein an image detector is mounted within a rare earth permanent magnet structure with a hollow cavity and an access port that passes through the structure and thereby accessing the cavity. The shell is permanently magnetized to produce a substantially uniform magnetic field in the cavity. The shell's magnetization is the resultant of two magnetization components M1 and M2. M2 components are uniform in both magnitude and direction while M1 components are uniform in magnitude but not uniform in direction. Preferably, the magnitudes of the M1 and M2 components are substantially equal to each other but aligned in opposite directions in regions adjacent to the access port. The image detector located within the cavity of the magnet is oriented such that the magnetic flux in the cavity flows in the same direction as the electron beam passing through the cavity.

Abstract: An optic modulator which employs strained multiple quantum well structures which are fabricated and spaced from one another such that the stress perpendicular to the direction of the spacing is released leaving only a uniaxial stress along the direction parallel to the spacing. The multiple quantum well structures are then sandwiched between two optic polarizers which are aligned perpendicular to one another. At zero electric field, polarized light passing from the first polarizer is further polarized such that the polarization of the light is rotated to pass through the second polarizer. When an electric field is applied across the heterostructure, light passing through the heterostructure is not further polarized and therefore, the optic signal is interrupted. Thus, optic signals may be modulated with the contrast of polarizing modulators at the speed of superlattice heterostructures.

Abstract: A polar semiconductor quantum wire for use in electronic and opto-electronic devices. The polar semiconductor quantum wire is either completely or partially encapsulated in metal to reduce the strength of the scattering potential associated with interface optical phonons normally established at the lateral boundaries of polar semiconductor quantum wires. Metal alone or metal employed in conjunction with modulation doping enhances the transport of charge carriers within the polar semiconductor quantum wire.

Abstract: A device for generating pulses of radio frequency energy in response to pulses of laser light in which a circular wafer of GaAs has metallized annular layers ohmically bonded to the wafer by epitaxial GaAs layers, and an epitaxial layer of AlGaAs in the center of one of the annular epitaxial layers through which laser light is to be directed, there being a plurality of apertures in the metallized layer in contact with the AlGaAs epitaxial layer. In addition, an AlGaAs epitaxial layer may be formed opposite the first AlGaAs layer and an optical fiber is brought into contact with it so that laser light can be introduced at both sides of the wafer.

Abstract: A FFT buffer circuit having at least three FIFO buffers and a FIFO buffer lect circuit to separate incoming real-data into its in-phase and quadrature components and to output each component to a separate port for FFT, and also having a modified overflow detect circuit to automatically detect and eliminate overflow in the incoming real-data stream. In addition, the invention utilizes link hook-ups and receiver control signals for external control of both the automatic overflow reset and the data buffer timing.

Abstract: A microstrip transmission line substrate to substrate transition is provi comprising a pair of spaced-apart dielectric substrates having facing inner surfaces and ground planes on the non-facing outer surfaces and a parallelepiped-shaped dielectric waveguide element sandwiched between the substrate inner surfaces. The waveguide element has a pair of rhomboidal-shaped sides and a pair of sloping ends. A first microstrip conductor is disposed on the inner surface of one of the substrates and the upwardly-sloping end of the waveguide element contiguous to that surface. A second microstrip conductor is disposed on the inner surface of the other substrate and the other sloping end of the waveguide element, so that a pair of mutually-inverted microstrip transmission lines is formed. The dielectric constant of the material of the substrates is preferably much less than the dielectric constant of the waveguide element material.