Patents by Inventor Sudhakar K. Rao

Sudhakar K. Rao 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: 10135137
    Abstract: A phased array antenna system including a front-end circuit having a plurality of antenna channels, each including a front antenna element and a rear antenna element, that provides a spatially combined beam. Each antenna channel includes a beam scan phase shifter and a true time delay phase shifter through which the receive signals or the transmit signals propagate. The system further includes a back-end circuit spaced from the front-end circuit and including an antenna receiving the receive signals from the rear elements or transmitting the transmit signals to the rear elements. The back-end circuit further includes an ortho-mode transducer that separates the transmit signal or the receive signal into orthogonally polarized signals, and a pair of couplers and a pair of polarization phase shifters that combine to adjust the polarization of the transmit signal or the receive signal. The spatially combined beam is reconfigurable in beam shape and its location.
    Type: Grant
    Filed: February 20, 2015
    Date of Patent: November 20, 2018
    Assignee: Northrop Grumman Systems Corporation
    Inventors: Sudhakar K. Rao, Arun K. Bhattacharyya
  • Patent number: 9972897
    Abstract: A phased array antenna including a plurality of antenna element units mounted to a panel having a first side and a second side. Each antenna unit includes a step aperture integrated radiating (STAIR) antenna element mounted to the first side of the panel and having an outer cylindrical waveguide, a septum polarizer including a plurality of steps and a septum feed structure, and a right hand circularly polarized (RHCP) feed structure electrically coupled to the septum feed structure. Each antenna unit further includes a triplexer module mounted to the second side of the panel and being responsive to a plurality of linearly polarized signals to be transmitted by the STAIR element, where the triplexer module operates to combine the plurality of linearly polarized signals and provide the combined signal to the RHCP feed structure to be converted by the septum polarizer to a circularly polarized signal for transmission.
    Type: Grant
    Filed: August 9, 2017
    Date of Patent: May 15, 2018
    Assignees: Northrop Grumman Systems Corporation, Custom Microwave Inc.
    Inventors: Sudhakar K. Rao, Clency Lee-Yow, Philip E. Venezia, Jonathan R. Scupin
  • Patent number: 9698492
    Abstract: A multiple beam integrated antenna system for a satellite including a support structure having an alignment plate. The antenna system further includes a plurality of feed horns mounted to the alignment plate, where each feed horn includes a plurality of tapered sections that support propagation modes for both up-link signals and down-link signals. A septum polarizer is mounted to an input end of each feed horn that converts linearly polarized signals to circularly polarized signals for the up-link signals and converts circularly polarized signals to linearly polarized signals for the down-link signals. A Y-shaped waveguide is coupled to each of the polarizers and includes separate receive reject and transmit reject filters so as to keep the up-link signals and the down-link signals from interfering with each other. Flex waveguides couple the transmit leg and the receive leg of each Y-shaped waveguide to RF modules.
    Type: Grant
    Filed: January 28, 2015
    Date of Patent: July 4, 2017
    Assignee: Northrop Grumman Systems Corporation
    Inventors: Sudhakar K. Rao, Daniel H. Roper, Arun K. Bhattacharyya
  • Patent number: 9666948
    Abstract: An inter-satellite cross-link antenna for a communications satellite in a constellation of satellites in earth orbit. The complete cross-link system is an array of eight quadrifilar helix antennas with a new design which is eight times smaller than previous designs, and has superior inter-satellite communications performance. The quadrifilar helix antenna is designed with a length, diameter, helix pitch angle and ground plate connectivity which is matched to the UHF inter-satellite communication frequency to provided a toroidal radiation pattern with high signal strength in a direction normal to the antenna axis and very low signal strength in an axial direction. The array of eight quadrifilar helix antennas does not require interleaving with the L-band GPS antenna aperture on the satellite, and does not block or interfere with the earth-directed GPS signals.
    Type: Grant
    Filed: February 2, 2016
    Date of Patent: May 30, 2017
    Assignee: Northrop Grumman Systems Corporation
    Inventors: Sudhakar K. Rao, Sebong Chun
  • Patent number: 9590299
    Abstract: A dual-reflector inter-satellite link (ISL) subsystem, for a communications satellite in a constellation of satellites in low earth orbit or medium earth orbit. The ISL subsystem includes a main antenna reflector which uses a single-axis gimbal to steer the main reflector only in the elevation plane. An antenna subreflector, a horn and RF feed circuitry are stationary with respect to the host satellite. The main reflector has a super-elliptical design which provides a beam shape which requires no steering in the azimuth plane, while meeting ISL signal strength requirements. By steering the main reflector only, and only in the elevation plane, the disclosed ISL subsystem delivers significantly lower size, mass, complexity and cost, and significantly greater reliability, than traditional ISL systems.
    Type: Grant
    Filed: June 15, 2015
    Date of Patent: March 7, 2017
    Assignee: Northrop Grumman Systems Corporation
    Inventors: Sudhakar K. Rao, Daniel H. Roper, Alan M. Taft, Sebong Chun, Christopher S. Brown, Mansoor K. Siddique
  • Publication number: 20160365630
    Abstract: A dual-reflector inter-satellite link (ISL) subsystem, for a communications satellite in a constellation of satellites in low earth orbit or medium earth orbit, is disclosed. The ISL subsystem includes a main antenna reflector which uses a single-axis gimbal to steer the main reflector only in the elevation plane. An antenna subreflector, a horn and RF feed circuitry are stationary with respect to the host satellite. The main reflector has a super-elliptical design which provides a beam shape which requires no steering in the azimuth plane, while meeting ISL signal strength requirements. By steering the main reflector only, and only in the elevation plane, the disclosed ISL subsystem delivers significantly lower size, mass, complexity and cost, and significantly greater reliability, than traditional ISL systems.
    Type: Application
    Filed: June 15, 2015
    Publication date: December 15, 2016
    Inventors: SUDHAKAR K. RAO, Daniel H. Roper, Alan M. Taft, Sebong Chun, Christopher S. Brown, Mansoor K. Siddique
  • Patent number: 9502780
    Abstract: An exemplary antenna array has first self-complementary antenna cells, e.g. bowtie antennas, disposed in a first plane in rows and columns. Additional bowtie antenna cells are disposed in a second plane parallel to the first plane and are aligned in corresponding rows and columns. A first stripline disposed between the first and second planes carries RF signals to/from the first and second bowtie antenna cells. A slot feed couples the RF signals between the first stripline and each of the first and second bowtie antenna cells. A conductive layer in a third plane parallel to the first and second planes serves as a ground plane for signals radiated from/to the first and second bowtie antenna cells.
    Type: Grant
    Filed: January 15, 2015
    Date of Patent: November 22, 2016
    Assignee: Northrop Grumman Systems Corporation
    Inventors: Loc B. Chau, Sudhakar K. Rao, Steven J. Mass, Dana Quincey
  • Publication number: 20160248157
    Abstract: A phased array antenna system including a front-end circuit having a plurality of antenna channels, each including a front antenna element and a rear antenna element, that provides a spatially combined beam. Each antenna channel includes a beam scan phase shifter and a true time delay phase shifter through which the receive signals or the transmit signals propagate. The system further includes a back-end circuit spaced from the front-end circuit and including an antenna receiving the receive signals from the rear elements or transmitting the transmit signals to the rear elements. The back-end circuit further includes an ortho-mode transducer that separates the transmit signal or the receive signal into orthogonally polarized signals, and a pair of couplers and a pair of polarization phase shifters that combine to adjust the polarization of the transmit signal or the receive signal. The spatially combined beam is reconfigurable in beam shape and its location.
    Type: Application
    Filed: February 20, 2015
    Publication date: August 25, 2016
    Inventors: SUDHAKAR K. RAO, ARUN K. BHATTACHARYYA
  • Publication number: 20160218436
    Abstract: A multiple beam integrated antenna system for a satellite including a support structure having an alignment plate. The antenna system further includes a plurality of feed horns mounted to the alignment plate, where each feed horn includes a plurality of tapered sections that support propagation modes for both up-link signals and down-link signals. A septum polarizer is mounted to an input end of each feed horn that converts linearly polarized signals to circularly polarized signals for the up-link signals and converts circularly polarized signals to linearly polarized signals for the down-link signals. A Y-shaped waveguide is coupled to each of the polarizers and includes separate receive reject and transmit reject filters so as to keep the up-link signals and the down-link signals from interfering with each other. Flex waveguides couple the transmit leg and the receive leg of each Y-shaped waveguide to RF modules.
    Type: Application
    Filed: January 28, 2015
    Publication date: July 28, 2016
    Inventors: SUDHAKAR K. RAO, DANIEL H. ROPER, ARUN K. BHATTACHARYYA
  • Publication number: 20160211585
    Abstract: An exemplary antenna array has first self-complementary antenna cells, e.g. bowtie antennas, disposed in a first plane in rows and columns. Additional bowtie antenna cells are disposed in a second plane parallel to the first plane and are aligned in corresponding rows and columns. A first stripline disposed between the first and second planes carries RF signals to/from the first and second bowtie antenna cells. A slot feed couples the RF signals between the first stripline and each of the first and second bowtie antenna cells. A conductive layer in a third plane parallel to the first and second planes serves as a ground plane for signals radiated from/to the first and second bowtie antenna cells.
    Type: Application
    Filed: January 15, 2015
    Publication date: July 21, 2016
    Inventors: Loc B. Chau, Sudhakar K. Rao, Steven J. Mass, Dana Quincey
  • Patent number: 9246234
    Abstract: An exemplary embodiment of an antenna in accordance with the present invention utilizes a sub-reflector and a main reflector with each of them having its own focal-ring type geometry. The antenna cooperates with a signal transmission feed disposed at the center of the antenna axis between the first and main reflectors to emit radio signals towards the sub-reflector. The sub-reflector reflects radio waves towards a main reflector which in turn reflects the radio waves to form the beam pattern emitted by the antenna. The reflecting surface of the sub-reflector is formed by a portion of an axially-displaced ellipse rotated about the antenna axis. The reflecting surface of the main reflector is defined by a section of a parabola rotated about the antenna axis to form a reflecting surface that concavely slopes away from the antenna axis. An embodiment of the antenna provides a wide coverage conical beam with selectable beam peaks that operate over a 2.
    Type: Grant
    Filed: September 24, 2013
    Date of Patent: January 26, 2016
    Assignee: Northrop Grumman Systems Corporation
    Inventors: Sudhakar K. Rao, Sebong Chun
  • Publication number: 20150084821
    Abstract: An exemplary embodiment of an antenna in accordance with the present invention utilizes a sub-reflector and a main reflector with each of them having its own focal-ring type geometry. The antenna cooperates with a signal transmission feed disposed at the center of the antenna axis between the first and main reflectors to emit radio signals towards the sub-reflector. The sub-reflector reflects radio waves towards a main reflector which in turn reflects the radio waves to form the beam pattern emitted by the antenna. The reflecting surface of the sub-reflector is formed by a portion of an axially-displaced ellipse rotated about the antenna axis. The reflecting surface of the main reflector is defined by a section of a parabola rotated about the antenna axis to form a reflecting surface that concavely slopes away from the antenna axis. An embodiment of the antenna provides a wide coverage conical beam with selectable beam peaks that operate over a 2.
    Type: Application
    Filed: September 24, 2013
    Publication date: March 26, 2015
    Applicant: Northrop Grumman Systems Corporation
    Inventors: Sudhakar K. Rao, Sebong Chun
  • Patent number: 8957821
    Abstract: A dual-band feed horn having a connection surface configured for connection to a waveguide and a first surface coupled to the connection surface. The first surface has a cylindrical surface with a length and a first diameter chosen to propagate TE11 modes for both a low frequency band and a high frequency band. The horn has a bandwidth ratio of the high-frequency band to the low frequency band in the range of 1.6-4.0. The horn also has a substantially conical surface coupled to the first surface at a first slope discontinuity. The conical surface includes multiple surfaces each having a respective slope and coupled to adjacent surfaces by a respective plurality of slope discontinuities each having a respective diameter. The slopes and diameters are chosen to generate primarily TM1,m modes (m=1, 2, 3, etc.) in the high-frequency band and primarily higher order TE1,n modes (n=2, 3, etc.) in the low-frequency band such that the low frequency band and the high frequency band have approximately equal beam widths.
    Type: Grant
    Filed: August 15, 2013
    Date of Patent: February 17, 2015
    Assignee: Lockheed Martin Corporation
    Inventors: Sudhakar K. Rao, Chih-Chien Hsu, Gerard J. Matyas
  • Patent number: 8514140
    Abstract: A dual-band antenna system configured to transmit and/or receive microwave beams over two or more frequency bands with substantially similar beam widths and substantially similar sidelobe levels is disclosed. The antenna system includes at least one reflector and at least one feed horn, the horn configured to provide a first efficiency over a first frequency band and lower efficiencies over one or more second frequency bands. The horn includes a substantially conical wall having an internal surface with a variable slope. The internal surface includes one or more slope discontinuities, wherein the slope discontinuities are configured to generate primarily TE1,m modes within the first frequency band and within the second frequency bands and generate TM1,n modes substantially only within the second frequency bands.
    Type: Grant
    Filed: February 25, 2010
    Date of Patent: August 20, 2013
    Assignee: Lockheed Martin Corporation
    Inventors: Sudhakar K. Rao, Chih-Chien Hsu, Gerard J. Matyas
  • Patent number: 8354956
    Abstract: A antenna system for generating and distributing power among a plurality of non-focused beams is provided The system comprises a reflector having a focal plane and a non-parabolic curvature configured to form the defocused beams. The curvature is configured to create a symmetrical quadratic phase-front in an aperture plane of the reflector. The system further comprises a plurality of feed antennas disposed in the focal plane of the reflector and configured to illuminate the reflector. Each feed antenna is configured to contribute power toward each of the defocused beams. The system further comprises a plurality of fixed-amplitude amplifiers, at least one of which corresponds to each feed antenna.
    Type: Grant
    Filed: June 25, 2009
    Date of Patent: January 15, 2013
    Assignee: Lockheed Martin Corporation
    Inventors: Gerard J. Matyas, Sudhakar K. Rao, Alan L. Stern, Minh Tang, William J. Taft, Ronald M. Hirschfield
  • Publication number: 20120105293
    Abstract: A horn antenna includes smooth-walls with multiple slope discontinuities. The horn antenna may have more than an octave bandwidth with a 2.25:1 bandwidth ratio to cover the frequencies of 20 GHz, 30 GHz, and 45 GHz, or all the desired bands for military or other communications.
    Type: Application
    Filed: June 11, 2008
    Publication date: May 3, 2012
    Applicant: LOCKHEED MARTIN CORPORATION, A Maryland Corporation
    Inventors: Chih-Chien Hsu, Sudhakar K. Rao
  • Patent number: 8164533
    Abstract: A horn antenna includes smooth-walls with multiple slope discontinuities. The horn antenna may have more than an octave bandwidth with a 2.25:1 bandwidth ratio to cover the frequencies of 20 GHz, 30 GHz, and 45 GHz, or all the desired bands for military or other communications.
    Type: Grant
    Filed: June 11, 2008
    Date of Patent: April 24, 2012
    Assignee: Lockhead Martin Corporation
    Inventors: Chih-Chien Hsu, Sudhakar K. Rao
  • Patent number: 7868840
    Abstract: An antenna system includes a reflector having a modified-paraboloid shape; and a multi-beam, multi-band feed array located at a focal point of the reflector so that the antenna system forms a multiple congruent beams that are contiguous. The system has a single reflector with non-frequency selective surface. The reflector is sized to produce a required beam size at K-band frequencies and is oversized at EHF-band frequencies. The synthesized reflector surface is moderately shaped and disproportionately broadens EHF-band and Ka-band beams compared to K-band beams. The synthesized reflector surface forms multiple beams each having a 0.5-degree diameter at K-band, Ka-band, and EHF band. The multi-beam, multi-band feed array includes a number of high-efficiency, multi-mode circular horns that operate in focused mode at K-band and defocused mode at Ka-band and EHF-band by employing “frequency-dependent” design for the horns.
    Type: Grant
    Filed: June 30, 2008
    Date of Patent: January 11, 2011
    Assignee: The Boeing Company
    Inventors: Sudhakar K. Rao, David Bressler
  • Patent number: 7750859
    Abstract: Methods, systems, and apparatus are disclosed for high power thermal vacuum testing of satellite payloads using pick-up horns. Such pick-up horns can include at least one outer metal wall forming a metal body and at least one interior surface disposed in the metal body, forming at least one chamber in the metal body. The pick-up horn further includes a front metal surface disposed at a front end of the metal body, having at least one opening corresponding to the at least one chamber, and at least one high-power absorbing load disposed within the at least one chamber and in contact with the at least one interior surface. A pick-up horn may further include a serpentine coolant path disposed within the metal body between an outer surface of the at least one outer metal wall and the at least one high-power absorbing load. Related systems and methods are described.
    Type: Grant
    Filed: January 18, 2008
    Date of Patent: July 6, 2010
    Assignee: Lockheed Martin Corporation
    Inventors: Sudhakar K. Rao, Clency Lee-Yow, Philip Venezia, Mark W. MacGregor
  • Patent number: 7737904
    Abstract: An antenna system for transmitting and/or receiving radio frequency (RF) signals in multiple frequency bands includes a horn antenna and a feed network. The horn antenna may transmit and/or receive RF signals in multiple frequency bands that are spread over more than an octave bandwidth with at least a 2.44-to-1 bandwidth ratio. The horn antenna includes a throat, an aperture, and an interior surface. The feed network includes a first waveguide section, a first junction, one or more first filters, and a first step-down waveguide section. The first waveguide section can provide a matching network and transmit and/or receive the RF signals in the multiple frequency bands. The first junction can transmit and/or receive the RF signals in first selected band(s) of the multiple frequency bands. The first step-down waveguide section may transmit and/or receive the RF signals in second selected band(s) of the multiple frequency bands.
    Type: Grant
    Filed: June 11, 2008
    Date of Patent: June 15, 2010
    Assignee: Lockheed Martin Corporation
    Inventors: Sudhakar K. Rao, Chris G. Baran, Chih-Chien Hsu, Surjit S. Dhillon