Patents by Inventor Toshiaki Shirosaka

Toshiaki Shirosaka 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: 7277063
    Abstract: Folded dipole antenna elements (2, 4) are disposed generally in parallel, being spaced by a distance smaller than a half of the wavelength employed. The antenna elements (2, 4) are connected to a combiner (16) via feeders (12, 14) having different lengths. The difference in length between the feeders (12, 14) is such that received signals resulting from a radio wave coming to the antenna elements (2, 4) from the front and received by the antenna elements (12, 14) are in phase with each other at the inputs (16a, 16b) of the combiner (16), whereas received signals resulting from a radio wave coming to the antenna elements (2, 4) from the back and received by the antenna elements (12, 14) are 180° out of phase with each other at the inputs (16a, 16b) of the combiner (16).
    Type: Grant
    Filed: April 1, 2004
    Date of Patent: October 2, 2007
    Assignee: DX Antenna Company, Limited
    Inventors: Toshiaki Shirosaka, Shingo Fujisawa, Toshio Fujita, Kiyotaka Tatekawa, Eiji Shibuya
  • Patent number: 7205955
    Abstract: A transmission line includes transmission lines parallel and perpendicular, respectively, to a flat portion of a reflector, and the parallel transmission line and the flat portion form a first strip line and the perpendicular transmission line and a conductive plate similarly form a second strip line. Radiators and the transmission line have a radiation impedance and a characteristic impedance, respectively, both set at 150? when the antenna's output terminal has a reference impedance of 75?. If the parallel transmission line has a midpoint serving as the output terminal of the antenna this portion's receiving current is divided in two so that an impedance of half that of the strip line can be provided and a coaxial cable can directly be connected to the transmission line. A matcher or a mixer is not included in the antenna, and matching and mixing losses can be prevented.
    Type: Grant
    Filed: September 30, 2005
    Date of Patent: April 17, 2007
    Assignee: DX Antenna Company, Limited
    Inventors: Toshiaki Shirosaka, Shingo Fujisawa
  • Patent number: 7084829
    Abstract: A signal receiving system includes a variable directivity antenna having its directivity varied in accordance with a control signal applied thereto. A control signal generator generating the control signal is provided in a receiving apparatus. The receiving apparatus includes also a modulator operating to ASK (amplitude-shift-keying) modulate a carrier with the control signal from the control signal generator into an ASK modulated signal. The ASK modulated signal is applied through a transmission line to the variable directivity antenna, and a controller associated with the variable directivity antenna demodulates the ASK modulated signal to recover the control signal for use in varying the directivity of the variable directivity antenna.
    Type: Grant
    Filed: March 9, 2004
    Date of Patent: August 1, 2006
    Assignee: DX Antenna Company, Limited
    Inventors: Toshiaki Shirosaka, Toshio Fujita, Kiyotaka Tatekawa, Shingo Fujisawa
  • Patent number: 7071891
    Abstract: First, second, third and fourth dipole antennas (14, 16, 18, 20) are disposed in a casing (1). The first through fourth dipole antennas are arranged in the same plane, and are disposed in line symmetry with respect to first through fourth imaginary lines (A, B, C, D) passing through the center of the casing (1) at an angle of 45 degrees between adjacent imaginary lines.
    Type: Grant
    Filed: March 10, 2005
    Date of Patent: July 4, 2006
    Assignee: DX Antenna Company, Limited
    Inventors: Toshiaki Shirosaka, Kiyotaka Tatekawa, Toshio Fujita
  • Publication number: 20060139230
    Abstract: A transmission line includes transmission lines parallel and perpendicular, respectively, to a flat portion of a reflector, and the parallel transmission line and the flat portion form a first strip line and the perpendicular transmission line and a conductive plate similarly form a second strip line. Radiators and the transmission line have a radiation impedance and a characteristic impedance, respectively, both set at 150 ? when the antenna's output terminal has a reference impedance of 75 ?. If the parallel transmission line has a midpoint serving as the output terminal of the antenna this portion's receiving current is divided in two so that an impedance of half that of the strip line can be provided and a coaxial cable can directly be connected to the transmission line. A matcher or a mixer is not included in the antenna, and matching and mixing losses can be prevented.
    Type: Application
    Filed: September 30, 2005
    Publication date: June 29, 2006
    Inventors: Toshiaki Shirosaka, Shingo Fujisawa
  • Publication number: 20060050005
    Abstract: Folded dipole antenna elements (2, 4) are disposed generally in parallel, being spaced by a distance smaller than a half of the wavelength employed. The antenna elements (2, 4) are connected to a combiner (16) via feeders (12, 14) having different lengths. The difference in length between the feeders (12, 14) is such that received signals resulting from a radio wave coming to the antenna elements (2, 4) from the front and received by the antenna elements (12, 14) are in phase with each other at the inputs (16a, 16b) of the combiner (16), whereas received signals resulting from a radio wave coming to the antenna elements (2, 4) from the back and received by the antenna elements (12, 14) are 180° out of phase with each other at the inputs (16a, 16b) of the combiner (16).
    Type: Application
    Filed: April 1, 2004
    Publication date: March 9, 2006
    Inventors: Toshiaki Shirosaka, Shingo Fujisawa, Toshio Fujita, Kiyotaka Takekawa, Eiji Shibuya
  • Publication number: 20060044203
    Abstract: First, second, third and fourth dipole antennas (14, 16, 18, 20) are disposed in a casing (1). The first through fourth dipole antennas are arranged in the same plane, and are disposed in line symmetry with respect to first through fourth imaginary lines (A, B, C, D) passing through the center of the casing (1) at an angle of 45 degrees between adjacent imaginary lines.
    Type: Application
    Filed: March 10, 2005
    Publication date: March 2, 2006
    Inventors: Toshiaki Shirosaka, Kiyotaka Tatekawa, Toshio Fujita
  • Patent number: 6965353
    Abstract: A multiple frequency band antenna includes a dipole antenna (4a), which is formed of two dipole antenna elements (8a, 10a). Two extension elements (24a, 26a) extend outward from respective ones of opposed outer ends of the dipole antenna (4a). The length of the dipole antenna (4a) is determined to make the multiple frequency band antenna capable of receiving radio waves in the UHF band, and the sum of the lengths of the dipole antenna (4a) and the extension elements (24a, 26a) is determined to make the multiple frequency band antenna capable of receiving radio waves in the VHF band. PIN diodes (28a, 34a) are connected between the respective extension elements (24a, 26a) and the respective outer ends of the dipole antenna (4a).
    Type: Grant
    Filed: April 12, 2004
    Date of Patent: November 15, 2005
    Assignee: DX Antenna Company, Limited
    Inventors: Toshiaki Shirosaka, Toshio Fujita, Kiyotaka Tatekawa, Shingo Fujisawa, Eiji Shibuya
  • Patent number: 6933907
    Abstract: Folded dipole antenna elements (2, 4) are disposed generally in parallel, being spaced by a distance smaller than a quarter of the wavelength employed. The antenna elements (2, 4) are connected to a combiner (16) via feeders (12, 14) having different lengths. The difference in length between the feeders (12, 14) is such that received signals resulting from a radio wave coming to the antenna elements (2, 4) from the front and received by the antenna elements (12, 14) are in phase with each other at the inputs (16a, 16b) of the combiner (16), whereas received signals resulting from a radio wave coming to the antenna elements (2, 4) from the back and received by the antenna elements (12, 14) are 180° out of phase with each other at the inputs (16a, 16b) of the combiner (16).
    Type: Grant
    Filed: January 13, 2004
    Date of Patent: August 23, 2005
    Assignee: DX Antenna Company, Limited
    Inventors: Toshiaki Shirosaka, Shingo Fujisawa
  • Patent number: 6914558
    Abstract: An antenna device (2a) includes first and second dipole antennas (4a, 6a) spaced from each other by a distance smaller than a quarter of a received wavelength. An antenna device (2b) includes third and fourth dipole antennas (4a, 6a) spaced from each other by the distance and is disposed orthogonal to the antenna device (2a). A first phase adjusting circuit (104a) combines signals from the first and second antennas (4a, 6a) after adjusting their phases, in such a manner that the resultant combined signal selectively assumes a forward directivity state exhibiting a forward directivity and a backward directivity state exhibiting a backward directivity. Similarly, a second phase adjusting circuit (104b) combines signals from the third and fourth antennas (4b, 6b) after adjusting their phases, in such a manner that the resultant combined signal selectively assumes a rightward directivity state exhibiting a rightward directivity and a leftward directivity state exhibiting a leftward directivity.
    Type: Grant
    Filed: October 29, 2004
    Date of Patent: July 5, 2005
    Assignee: DX Antenna Company, Limited
    Inventors: Toshiaki Shirosaka, Toshio Fujita, Kiyotaka Tatekawa, Eiji Shibuya
  • Publication number: 20050062667
    Abstract: A multiple frequency band antenna includes a dipole antenna (4a), which is formed of two dipole antenna elements (8a, 10a). Two extension elements (24a, 26a) extend outward from respective ones of opposed outer ends of the dipole antenna (4a). The length of the dipole antenna (4a) is determined to make the multiple frequency band antenna capable of receiving radio waves in the UHF band, and the sum of the lengths of the dipole antenna (4a) and the extension elements (24a, 26a) is determined to make the multiple frequency band antenna capable of receiving radio waves in the VHF band. PIN diodes (28a, 34a) are connected between the respective extension elements (24a, 26a) and the respective outer ends of the dipole antenna (4a).
    Type: Application
    Filed: April 12, 2004
    Publication date: March 24, 2005
    Inventors: Toshiaki Shirosaka, Toshio Fujita, Kiyotaka Tatekawa, Shingo Fujisawa, Eiji Shibuya
  • Publication number: 20040196202
    Abstract: Folded dipole antenna elements (2, 4) are disposed generally in parallel, being spaced by a distance smaller than a quarter of the wavelength employed. The antenna elements (2, 4) are connected to a combiner (16) via feeders (12, 14) having different lengths. The difference in length between the feeders (12, 14) is such that received signals resulting from a radio wave coming to the antenna elements (2, 4) from the front and received by the antenna elements (12, 14) are in phase with each other at the inputs (16a, 16b) of the combiner (16), whereas received signals resulting from a radio wave coming to the antenna elements (2, 4) from the back and received by the antenna elements (12, 14) are 180° out of phase with each other at the inputs (16a, 16b) of the combiner (16).
    Type: Application
    Filed: January 13, 2004
    Publication date: October 7, 2004
    Inventors: Toshiaki Shirosaka, Shingo Fujisawa
  • Publication number: 20040196204
    Abstract: A signal receiving system includes a variable directivity antenna having its directivity varied in accordance with a control signal applied thereto. A control signal generator generating the control signal is provided in a receiving apparatus. The receiving apparatus includes also a modulator operating to ASK (amplitude-shift-keying) modulate a carrier with the control signal from the control signal generator into an ASK modulated signal. The ASK modulated signal is applied through a transmission line to the variable directivity antenna, and a controller associated with the variable directivity antenna demodulates the ASK modulated signal to recover the control signal for use in varying the directivity of the variable directivity antenna.
    Type: Application
    Filed: March 9, 2004
    Publication date: October 7, 2004
    Inventors: Toshiaki Shirosaka, Toshio Fujita, Kiyotaka Tatekawa, Shingo Fujisawa
  • Patent number: 6774863
    Abstract: Antennas (8a-8d) are disposed within an antenna body (2) of an antenna system in such a manner as to receive UHF band radio waves coming to the main body (2) from a plurality of first, different directions around the main body (2). Combinations of the antennas (8a-8d) makes the antenna system possible to receive UHF band radio waves coming to the main body (2) from a plurality of second, different directions between adjacent ones of the first directions. Switches (26a-26d) disposed within the main body (2) select one of outputs provided by the individual antennas (8a-8d) and their combinations. An antenna controller (64a), a unit separate from the main body (2), supplies a selection control signal to the switches (26a-26d).
    Type: Grant
    Filed: February 3, 2003
    Date of Patent: August 10, 2004
    Assignee: DX Antenna Company, Limited
    Inventors: Toshiaki Shirosaka, Kiyotaka Tatekawa, Eiji Shibuya, Shingo Fujisawa, Shotaro Horii
  • Publication number: 20040102221
    Abstract: Antennas (8a-8d) are disposed within an antenna body (2) of an antenna system in such a manner as to receive UHF band radio waves coming to the main body (2) from a plurality of first, different directions around the main body (2). Combinations of the antennas (8a-8d) makes the antenna system possible to receive UHF band radio waves coming to the main body (2) from a plurality of second, different directions between adjacent ones of the first directions. Switches (26a-26d) disposed within the main body (2) select one of outputs provided by the individual antennas (8a-8d) and their combinations. An antenna controller (64a), a unit separate from the main body (2), supplies a selection control signal to the switches (26a-26d).
    Type: Application
    Filed: February 3, 2003
    Publication date: May 27, 2004
    Inventors: Toshiaki Shirosaka, Kiyotaka Tatekawa, Eiji Shibuya, Shingo Fujisawa, Shotaro Horii
  • Patent number: 5006858
    Abstract: A microstrip line antenna generally used for receiving an electric wave from an artificial satellite, which comprises a plane dielectric substrate and a plurality of crank-shaped microstrip lines arranged on the substrate. The improvement comprises a number of half wavelength waveguide elements arranged on a plane lying parallel to the substrate in front of the microstrip lines at a predetermined distance therefrom for improving the signal-to-noise ratio of the antenna and reducing the number of antenna elements.
    Type: Grant
    Filed: January 8, 1990
    Date of Patent: April 9, 1991
    Assignee: DX Antenna Company, Limited
    Inventor: Toshiaki Shirosaka
  • Patent number: 4988963
    Abstract: A high frequency coaxial line coupling device which is insertable along the length of a coaxial line such as that which connects a rotary antenna carried on a moving body such as vehicle or vessel to receive a signal from a communication or broadcast satellite, with a receiver component such as tuner fixed to the moving body, for the purpose of allowing free relative rotation of the two segments of the coaxial line separated by the coupling device and preventing twist or entanglement of the coaxial line caused by rotation of the antenna with turning movement of the moving body. The device structure provides for a low transmission loss characteristic over a wide frequency range.
    Type: Grant
    Filed: January 8, 1990
    Date of Patent: January 29, 1991
    Assignee: DX Antenna Company, Limited
    Inventors: Toshiaki Shirosaka, Nobuyuki Ten