Abstract: An apparatus for frequency up conversion and down conversion using frequency multiplier circuits. The frequency multiplier circuits receive a lower frequency signal and are operated in a forward direction to provide a higher frequency output. The same frequency multiplier circuits are operated in a reverse direction by receiving a higher frequency signal and producing a lower frequency output. The frequency multiplier circuits preferably use heterojunction barrier varactor diodes to eliminate the need for DC bias or idler circuitry.

Abstract: A device for varying the capacitance of an electronic circuit is disclosed. The device comprises a flexible membrane located above the electronic circuit, a metal layer connected to the flexible membrane, and bias circuitry located above the membrane. Variation of the capacitance of the electronic circuit is obtained by pulling the membrane upwards by means of the bias circuitry. The disclosed device provides a sizeable capacitance variation and high Q factor, resulting in overall low filter insertion loss. A nearly constant group delay over a wide operating bandwidth is also obtained.

Abstract: A method for guiding waves over objects, a method for improving a performance of an antenna, and a method for improving a performance of a radar are disclosed. The methods disclosed teach how an impedance structure can be used to guide waves over objects.

Abstract: A control system (20) for a power converter (22) designed to convert DC power from a source (30) such as a battery, flywheel or fuel cell into AC power. The control system includes an impedance current regulator (106) for providing an impedance current signal to a summing unit (110) where it may be combined with real and reactive current command signals provided from respective sources (62, 64). The resultant current signal provided by the summing unit is provided to a voltage correction unit (112) that uses the resultant current signal in developing a correction voltage signal provided to the power converter. The correction voltage signal contains information used by the power converter in adjusting the real and reactive currents in its output AC power based on the ability of the AC power network to accept changes in current.

Abstract: A planar multi-layer transreflector for generating collimated coherent energy comprises one or more of insulating layers between two or more metallic layers. The transreflector substantially reflects a cross-polarized component of an incident millimeter-wave signal and substantially transmits the remaining portions of the incident millimeter-wave signal. Each of the metallic layers comprises a plurality of rectangles arranged in a grid pattern radially varying in size within circumferential regions. The reflected cross-polarized component may be substantially orthogonal to the transmitted remaining portions. A substantially collimated and coherent wavefront comprising the remaining portions may be produced in a first direction, and substantially collimated and coherent wavefront comprising the cross-polarized components may be produced in a second direction.

Abstract: A dual-band monopole antenna includes a ground plane. A metal plate is located a first distance from the ground plane and includes first and second portions connecting to form a first angle therebetween. A slot is formed in the metal plate that isolates a center portion of the metal plate. The dual-band monopole antenna communicates first radio frequency (RF) signals in a first RF band and second RF signals in a second RF band. A feed tab contacts an outer surface of the metal plate and is located the first distance from the ground plane. The first RF signals and the second RF signals are vertical polarized signals. The dual-band monopole antenna produces a radiation pattern that is omnidirectional in the azimuth plane and vertically polarized in a horizontal plane. The first RF band and the second RF band are independently tuned.

Abstract: A bias-line bypassing structure comprises a plurality of bias-line bypass circuits forming a periodic structure at least partially around each of a plurality of amplification units to reduce RF current flow between the amplification units and a grid-bias network. Each bias-line bypass circuit may comprise thin-film capacitors, inductive wire bridges, and thin-film resistors connected to ground vias. The thin-film capacitors may have differing values selected to resonate with an associated one of the inductive wire bridges and an associated one of the thin-film resistors to shunt RF current flow over a range of RF frequencies. In some embodiments, the inductive wire bridges may comprise inductive wire-bridge fuses to provide an open circuit in case an associated one the thin-film capacitors shorts to ground. The bias-line bypass circuits may be positioned along a bias street of the grid-bias network and spaced apart by less than a quarter-wavelength of an effective propagation constant of the bias line.

Abstract: A method and apparatus for generating an arbitrary UWB waveform are presented. An optical comb generator generates a serial stream of optical tones and an optical beating tone. A serial-to-parallel converter receives the serial tones and converts them into parallel optical tones. A spatial light modulator receives the parallel optical tones, and independently adjusts at least one of the phase and amplitude of each to generate the components of an arbitrary waveform. Next, each one of a plurality of optical-to-electrical converters receives a parallel optical tone and the selected optical beating tone, which are beat with the optical beating tone, producing electrical notes, representing differences between each parallel optical tones and the optical beating tone. Each antenna element is connected to receive an electrical note and to launch a signal based thereon, such that the launched signals are superimposed to the arbitrary waveform signal.

Abstract: A device for varying the capacitance of an electronic circuit is disclosed. The device comprises a flexible membrane located above the electronic circuit, a metal layer connected to the flexible membrane, and bias circuitry located above the membrane. Variation of the capacitance of the electronic circuit is obtained by pulling the membrane upwards by means of the bias circuitry. The disclosed device provides a sizeable capacitance variation and high Q factor, resulting in overall low filter insertion loss. A nearly constant group delay over a wide operating bandwidth is also obtained.

Abstract: The present invention provides a phosphorus solid-phase buffering system that can be spatially localized, i.e., banded on top of, or at specific depths, in media, e.g., soil, by which phosphorus concentrations in the media are reduced or maintained at levels sufficient for optimal plant performance. Also provided are methods for improving the cultivation of plants growing in different media. The present invention provides benefits, such as reduced water and pesticide requirements, reduced phosphorus leaching and runoff, and enhanced root growth. The invention can be used in connection with containerized or field-grown plants, e.g., crops, grasses, trees, and the like. The invention is particularly useful for greenhouse and nursery plants, ornamental propagation, vegetable and bedding transplants, and for turf used for stadium fields, golf courses, lawns and the like, where phosphorus leaching is particularly undesirable.

Abstract: A bias-line bypassing structure comprises a plurality of bias-line bypass circuits forming a periodic structure at least partially around each of a plurality of amplification units to reduce RF current flow between the amplification units and a grid-bias network. Each bias-line bypass circuit may comprise thin-film capacitors, inductive wire bridges, and thin-film resistors connected to ground vias. The thin-film capacitors may have differing values selected to resonate with an associated one of the inductive wire bridges and an associated one of the thin-film resistors to shunt RF current flow over a range of RF frequencies. In some embodiments, the inductive wire bridges may comprise inductive wire-bridge fuses to provide an open circuit in case an associated one the thin-film capacitors shorts to ground. The bias-line bypass circuits may be positioned along a bias street of the grid-bias network and spaced apart by less than a quarter-wavelength of an effective propagation constant of the bias line.

Abstract: A control system (20) for a power converter (22) designed to convert DC power from a source (30) such as a battery, flywheel or fuel cell into AC power. The control system includes an impedance current regulator (106) for providing an impedance current signal to a summing unit (110) where it may be combined with real and reactive current command signals provided from respective sources (62, 64). The resultant current signal provided by the summing unit is provided to a voltage correction unit (112) that uses the resultant current signal in developing a correction voltage signal provided to the power converter. The correction voltage signal contains information used by the power converter in adjusting the real and reactive currents in its output AC power based on the ability of the AC power network to accept changes in current.

Abstract: A control system (20) for a power converter (22) designed to convert DC power from a source (30) such as a battery, flywheel or fuel cell into AC power. The control system includes an impedance current regulator (106) for providing an impedance current signal to a summing unit (110) where it may be combined with real and reactive current command signals provided from respective sources (62, 64). The resultant current signal provided by the summing unit is provided to a voltage correction unit (112) that uses the resultant current signal in developing a correction voltage signal provided to the power converter. The correction voltage signal contains information used by the power converter in adjusting the real and reactive currents in its output AC power based on the ability of the AC power network to accept changes in current.

Abstract: A method and apparatus for generating an arbitrary UWB waveform are presented. An optical comb generator generates a serial stream of optical tones and an optical beating tone. A serial-to-parallel converter receives the serial tones and converts them into parallel optical tones. A spatial light modulator receives the parallel optical tones, and independently adjusts at least one of the phase and amplitude of each to generate the components of an arbitrary waveform. Next, each one of a plurality of optical-to-electrical converters receives a parallel optical tone and the selected optical beating tone, which are beat with the optical beating tone, producing electrical notes, representing differences between each parallel optical tones and the optical beating tone. Each antenna element is connected to receive an electrical note and to launch a signal based thereon, such that the launched signals are superimposed to the arbitrary waveform signal.

Abstract: A control system (20) for a power converter (22) designed to convert DC power from a source (30) such as a battery, flywheel or fuel cell into AC power. The control system includes an impedance current regulator (106) for providing an impedance current signal to a summing unit (110) where it may be combined with real and reactive current command signals provided from respective sources (62, 64). The resultant current signal provided by the summing unit is provided to a voltage correction unit (112) that uses the resultant current signal in developing a correction voltage signal provided to the power converter. The correction voltage signal contains information used by the power converter in adjusting the real and reactive currents in its output AC power based on the ability of the AC power network to accept changes in current.

Abstract: A multiband millimeterwave antenna system for communicating signals in multiple frequency bands is disclosed. A main antenna body is connected to antenna extensions by micro-electro-mechanical switches. By opening and closing the switches, the length of the antenna can be altered. The antenna is coupled to a microstrip feed line by an aperture. A series of matching stubs match the impedance of the feed line for the various signal frequencies.

Abstract: Methods for the design and fabrication of micro-electro-mechanical switches are disclosed. Two different switch designs with three different switch fabrication techniques are presented for a total of six switch structures. Each switch has a multiple-layer armature with a suspended biasing electrode and a conducting transmission line affixed to the structural layer of the armature. A conducting dimple is connected to the conducting line to provide a reliable region of contact for the switch. The switch is fabricated using silicon nitride as the armature structural layer and silicon dioxide as the sacrificial layer supporting the armature during fabrication. Hydrofluoric acid is used to remove the silicon dioxide layer with post-processing in a critical point dryer to increase yield.