Patents by Inventor George H. MacMaster

George H. MacMaster has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5196765
    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.
    Type: Grant
    Filed: July 5, 1988
    Date of Patent: March 23, 1993
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Lawrence J. Nichols
  • Patent number: 5142253
    Abstract: A cylindrical multi-port combiner having a graceful degradation characteristic with a high degree of isolation (25 db) between ports and a high combining efficiency (>90.degree.) is disclosed. A radially-spaced inner and outer conductor forms a transmission line operating in a balanced mode. Circumferentially spaced plurality of like transmission lines have inner and outer RF absorbers at the outermost regions of the spaced adjacent inner and outer conductors, respectively. A corresponding end of each transmission line in adapted to be connected to one of a corresponding number of phase-matched RF sources. The other end of each transmission line has its inner and outer conductors connected in parallel, respectively, through stepped impedance-transforming transmission lines to form one connector for connection to an output RF load.
    Type: Grant
    Filed: May 2, 1990
    Date of Patent: August 25, 1992
    Assignee: Raytheon Company
    Inventors: Raghuveer Mallavarpu, George H. MacMaster, M. Paul Puri
  • Patent number: 4928070
    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.
    Type: Grant
    Filed: February 28, 1989
    Date of Patent: May 22, 1990
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Lawrence J. Nichols
  • Patent number: 4763043
    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.
    Type: Grant
    Filed: December 23, 1985
    Date of Patent: August 9, 1988
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Lawrence J. Nichols
  • Patent number: 4742271
    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.
    Type: Grant
    Filed: April 10, 1987
    Date of Patent: May 3, 1988
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Lawrence J. Nichols
  • Patent number: 4677342
    Abstract: The cathode and tube of this invention comprise a secondary emission semiconductor cathode in a crossed-field high power amplifier. A gallium arsenide semiconductor doped with an impurity to make it more conductive than intrinsic gallium arsenide has been found to perform better than prior art secondary emission cathodes when it is incorporated as a cathode in a high-power crossed-field amplifier tube operating at high average and peak current. With a gallium arsenide cathode, the crossed-field amplifier tube exhibits a radio frequency output pulse which has fast rise time and much reduced leading-edge jitter relative to performance of the same cross-field amplifier tube having a conventional secondary emission cathode.
    Type: Grant
    Filed: February 1, 1985
    Date of Patent: June 30, 1987
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Lawrence J. Nichols
  • Patent number: 4434387
    Abstract: A crossed-field amplifier tube with a cathode slow wave structure at a high electrical potential is coupled to a high frequency of source and a load by a direct current isolated radio frequency transition. The transition is contained within the vacuum of the tube to prevent electrical breakdown between the transition and ground.
    Type: Grant
    Filed: July 6, 1981
    Date of Patent: February 28, 1984
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Lawrence J. Nichols
  • Patent number: 4429286
    Abstract: A divider/combiner amplifier circuit divides input power through a sectored coaxial line to a plurality of longitudinal parallel channels spaced around the circumference of a cylinder; the power in each channel is amplified by a semiconductor device; and the amplified power is combined in another sectored coaxial line. A microwave waveguide connected to the input and output of each amplifying device confines the microwave energy of the operating mode to the longitudinal channel formed by said waveguide. Each waveguide extends longitudinally along the cylinder and each is circumferentially spaced from its neighboring waveguide by a space which forms a cut-off waveguide to the operating mode.
    Type: Grant
    Filed: April 19, 1982
    Date of Patent: January 31, 1984
    Assignee: Raytheon Company
    Inventors: Lawrence J. Nichols, George H. MacMaster
  • Patent number: 4424496
    Abstract: A divider/combiner amplifier circuit divides input power through a sectored coaxial line to a plurality of longitudinal parallel channels spaced around the circumference of a cylinder; the power in each channel is amplified by a semiconductor device; and the amplified power is combined in another sectored coaxial line. A microwave waveguide connected to the input and output of each amplifying device confines the microwave energy of the operating mode to the longitudinal channel formed by said waveguide. Each waveguide extends longitudinally along the cylinder and each is circumferentially spaced from its neighboring waveguide by a space which forms a cut-off waveguide to the operating mode.
    Type: Grant
    Filed: October 13, 1981
    Date of Patent: January 3, 1984
    Assignee: Raytheon Company
    Inventors: Lawrence J. Nichols, George H. MacMaster
  • Patent number: 4349791
    Abstract: A system of slow wave structures for coupling a first electromagnetic circuit to a second electromagnetic circuit includes an inner slow wave structure and an outer slow wave structure concentric with the inner structure. The outer structure is configured to provide for a greater phase velocity of electromagnetc waves than the inner structure, the phase velocities for each structure being proportional to the circumference of each structure so that the rate of circulation of a wavefront about the common axis of the two structures is the same for a wave propagating about the inner structure and a wave propagating about the outer structure. The structures are terminated in their characteristic impedances to provide for wave propagation in one direction without reflections.
    Type: Grant
    Filed: August 21, 1980
    Date of Patent: September 14, 1982
    Assignee: Raytheon Company
    Inventors: Lawrence J. Nichols, George H. MacMaster
  • Patent number: 4296298
    Abstract: A dielectric heating oven having a set of parallel spaced electrodes alternately grounded and every ungrounded electrode fed by electromagnetic energy from a common source in an ISM band preferably from 13.56 megacycles to 40.68 megacycles. Food is placed on top of the electrodes and the depth of penetration of the electric fields into the food is a function of the phase relationship of the energized electrodes. When all energized electrodes are feed in the same phase, maximum field coupling is to the grounded electrodes between them resulting in high intensity searing electric fields close to the surface of the food. Deeper penetration cooking is accomplished by feeding adjacent energized electrodes 180.degree. out of phase so that maximum field coupling is between them rather to the grounded electrode between them. Still further penetration cooking results from feeding all adjacent energized electrodes 90.degree. out of phase so that maximum field coupling is to alternate energized electrodes.
    Type: Grant
    Filed: November 5, 1979
    Date of Patent: October 20, 1981
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Kenneth W. Dudley
  • Patent number: 4283685
    Abstract: A multiple channel amplifier providing both gain and/or phase shift to a microwave signal is formed of a set of transmission lines connected in parallel by means of a power splitter at the input end and a power combiner at the output end of the set of transmission lines. The transmission lines are disposed in a cylindrical array of electrically conducting bars which support amplifying and/or phase shifting elements between the bars and withdraw heat from the amplifying and/or phase shifting elements. The transmission lines may be slotted or severed for directing power flow towards an output terminal of the amplifier. The amplifying and/or phase shifting elements are conveniently mounted on a set of heat sinks to form modules, each of which is readily inserted and detached from the cylindrical array.
    Type: Grant
    Filed: December 13, 1979
    Date of Patent: August 11, 1981
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Lawrence J. Nichols
  • Patent number: 4282492
    Abstract: A multiple channel amplifier providing both gain and/or phase shift to a microwave signal is formed of a set of transmission lines connected in parallel by means of a power splitter at the input end and a power combiner at the output end of the set of transmission lines. The transmission lines are disposed in a cylindrical array of electrically conducting bars which support amplifying and/or phase shifting elements between the bars and withdraw heat from the amplifying and/or phase shifting elements. The transmission lines may be slotted or severed for directing power flow towards an output terminal of the amplifier. The amplifying and/or phase shifting elements are conveniently mounted on a set of heat sinks to form modules, each of which is readily inserted and detached from the cylindrical array.
    Type: Grant
    Filed: December 13, 1979
    Date of Patent: August 4, 1981
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Lawrence J. Nichols
  • Patent number: 4282491
    Abstract: A multiple channel amplifier providing both gain and/or phase shift to a microwave signal is formed of a set of transmission lines connected in parallel by means of a power splitter at the input end and a power combiner at the output end of the set of transmission lines. The transmission lines are disposed in a cylindrical array of electrically conducting bars which support amplifying and/or phase shifting elements between the bars and withdraw heat from the amplifying and/or phase shifting elements. The transmission lines may be slotted or severed for directing power flow towards an output terminal of the amplifier. The amplifying and/or phase shifting elements are conveniently mounted on a set of heat sinks to form modules, each of which is readily inserted and detached from the cylindrical array.
    Type: Grant
    Filed: December 13, 1979
    Date of Patent: August 4, 1981
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Lawrence J. Nichols
  • Patent number: 4272740
    Abstract: A multiple channel amplifier providing both gain and/or phase shift to a microwave signal is formed of a set of transmission lines connected in parallel by means of a power splitter at the input end and a power combiner at the output end of the set of transmission lines. The transmission lines are disposed in a cylindrical array of electrically conducting bars which support amplifying and/or phase shifting elements between the bars and withdraw heat from the amplifying and/or phase shifting elements. The transmission lines may be slotted or severed for directing power flow towards an output terminal of the amplifier. The amplifying and/or phase shifting elements are conveniently mounted on a set of heat sinks to form modules, each of which is readily inserted and detached from the cylindrical array.
    Type: Grant
    Filed: December 13, 1979
    Date of Patent: June 9, 1981
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Lawrence J. Nichols
  • Patent number: 3980920
    Abstract: A microwave oscillator is provided having electron emissive means and a first surrounding resonant structure. The first structure is fabricated of a material capable of emitting secondary electrons. A second resonant structure surrounds the secondary electron emitter and microwave energy is generated by the interaction between the electrons and currents induced in the structure. The high degree of isolation between the first oscillator section and the second amplifying section results in the generation of stable oscillations relatively free of effects of load variations.
    Type: Grant
    Filed: July 2, 1975
    Date of Patent: September 14, 1976
    Assignee: Raytheon Company
    Inventors: Kenneth W. Dudley, George H. MacMaster, Lawrence J. Nichols
  • Patent number: 3946187
    Abstract: A microwave browning and searing utensil for microwave ovens is provided having a plurality of conductive metal members each folded in such a manner as to provide a continuous apex portion and two substantially equidistant adjacent legs spaced apart and defining two free ends. The legs are substantially one-quarter of a wavelength in height. The induced electric currents along the legs results in a total current excursion of one-half of a wavelength to establish a 180.degree. phase reversal plus and minus mode adjacent to the exposed ends. Planar microwaves radiated within an oven enclosure are converted by the array of conductive members to provide an intense fringing electric field 180.degree. out-of-phase in close proximity to the material being heated. The fringing electric fields decay exponentially a short distance away from the exposed ends.
    Type: Grant
    Filed: March 3, 1975
    Date of Patent: March 23, 1976
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Kenneth W. Dudley
  • Patent number: 3941968
    Abstract: A microwave browning plate utilizing members of a relatively low dielectric constant material is provided having a conductive coating on three sides with a load supported on the uncoated side. The induced currents in the conductive material provides for current induced in the dielectric material. An exponentially decreasing fringing electric field is provided as a standing wave adjacent to the uncoated side. A low dielectric constant material may be utilized with the conductive coating and an overall height of one-quarter of a wavelength will result in a thinner microwave plate. Means are provided for restricting the current flow to a desired mode.
    Type: Grant
    Filed: March 27, 1975
    Date of Patent: March 2, 1976
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Kenneth W. Dudley
  • Patent number: 3934106
    Abstract: Apparatus is disclosed for heating with microwave energy utilizing nonresonant means for converting and transforming free space plane waves within the oven enclosure into fringing electric field patterns to brown or sear the load surfaces similar to broiling. One embodiment comprises parallel abutting plates with alternate plates of a high dielectric constant material to provide a predetermined phase lag and with the intervening low dielectric constant sections to provide alternating fringing electric fields, illustratively, in the pi or any other desired mode pattern. Alternate embodiments include microwave strip transmission lines comprising conductive strips separated by a dielectric substrate to couple and convert the free space waves into the desired heating mode pattern. A load supporting shelf within the microwave oven may be readily adapted to include the alternating dielectric materials to provide the desired fringing electric field patterns.
    Type: Grant
    Filed: August 14, 1974
    Date of Patent: January 20, 1976
    Assignee: Raytheon Company
    Inventors: George H. MacMaster, Kenneth W. Dudley
  • Patent number: 3933323
    Abstract: Solid state spaced-oriented means convert solar radiation into microwave energy which is amplified and beamed to earth as a source of electrical power. A large number of semiconductor devices operating in the current multiplication region are irradiated by single mode coherent light beam generation means which is pumped by solar energy. A neodymium yittrium aluminum iron garnet laser or CW gallium arsenide junction diode laser mode-locked at a predetermined microwave frequency, such as 3,000 MHz provide for generation of a light beam. The generated current is directly proportional to the radiant energy and is coupled from the semiconductor device array to antenna means for transmission to earth stations for conversion into low frequency electrical energy.
    Type: Grant
    Filed: March 20, 1974
    Date of Patent: January 20, 1976
    Assignee: Raytheon Company
    Inventors: Kenneth W. Dudley, George H. MacMaster