Patents by Inventor Sadao Yamashita

Sadao Yamashita 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: 5945894
    Abstract: A dielectric resonator capable of resonating at a predetermined resonance frequency has a dielectric substrate, a first electrode formed on a first surface of the dielectric substrate and having a first opening, a second electrode formed on a second surface of the dielectric substrate and having a second opening, a first conductor plate disposed by being spaced apart from the dielectric substrate by a predetermined distance, and a second conductor plate disposed by being spaced apart from the dielectric substrate by a predetermined distance, wherein at least one of said first and second conductor plates is electrically connected to at least one of said first and second electrodes.
    Type: Grant
    Filed: June 26, 1997
    Date of Patent: August 31, 1999
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Yohei Ishikawa, Toshiro Hiratsuka, Kenichi Iio, Sadao Yamashita
  • Patent number: 5920245
    Abstract: The ease of mounting a circuit board on a nonradiative dielectric line is improved, the degree of freedom of conductor film patterns formed on the circuit board is increased, and the degree of integration can be easily increased to fit within a small size. Dielectric strips are provided between the two conductor plates positioned in parallel to each other, and a circuit board is positioned parallel to the conductor plates. The conductor patterns on the circuit board and the transmission waves of the nonradiative dielectric line are electromagnetically coupled to each other.
    Type: Grant
    Filed: April 9, 1998
    Date of Patent: July 6, 1999
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Yohei Ishikawa, Toru Tanizaki, Hiroshi Nishida, Sadao Yamashita, Atsushi Saitoh
  • Patent number: 5872485
    Abstract: An amplifying circuit is formed by a combination of a dielectric line waveguide and a semiconductor device. Two electrically conductive plates are provided substantially parallel to each other. Two dielectric strips are disposed between the two conductive plates, and a dielectric plate is further inserted between the dielectric strips. Ground conductors are formed on the dielectric plate. The ground conductors have an area which equals an amount required for blocking a RF signal propagating in the dielectric line waveguide. A slot line is formed between the ground conductors in a position intermediate opposed sides of the dielectric strips. Line-switching conductor patterns are provided at both sides of the ends of the slot line. A field-effect transistor is mounted on the slot line such that it bridges over the slot line. Accordingly, losses and distortion of an RF signal, which would occur in an input/output circuit, are suppressed, and the generation of parasitic coupling is eliminated.
    Type: Grant
    Filed: July 28, 1997
    Date of Patent: February 16, 1999
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Yohei Ishikawa, Koichi Sakamoto, Sadao Yamashita, Takehisa Kajikawa
  • Patent number: 5786740
    Abstract: A dielectric resonator capable of adjusting a resonance frequency, reducing occurrence of a mode jump if it is applied to an oscillator and being manufactured at a low cost. The dielectric resonator has a pair of upper and lower opposing conductive plates; a dielectric substrate disposed between the conductive plates; a first electrode formed on one surface of the dielectric substrate, the first electrode having a first opening; a second electrode formed on another surface of the dielectric substrate, the second electrode having a second opening corresponding to the first opening so that a resonator is formed by a portion of the dielectric substrate disposed between the first and second openings; and a variable capacitor located in a portion of the dielectric substrate in which an applied electromagnetic field is confined in and around the resonator.
    Type: Grant
    Filed: September 19, 1996
    Date of Patent: July 28, 1998
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Yohei Ishikawa, Toshiro Hiratsuka, Sadao Yamashita, Kenichi Iio
  • Patent number: 5770989
    Abstract: The ease of mounting a circuit board on a nonradiative dielectric line is improved, the degree of freedom of conductor film patterns formed on the circuit board is increased, and the degree of integration can be easily increased to fit within a small size. Dielectric strips are provided between the two conductor plates positioned in parallel to each other, and a circuit board is positioned parallel to the conductor plates. The conductor patterns on the circuit board and the transmission waves of the nonradiative dielectric line are electromagnetically coupled to each other.
    Type: Grant
    Filed: July 3, 1996
    Date of Patent: June 23, 1998
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Yohei Ishikawa, Toru Tanizaki, Hiroshi Nishida, Sadao Yamashita, Atsushi Saitoh
  • Patent number: 5764116
    Abstract: A dielectric resonator capable of resonating at a predetermined resonance frequency has a dielectric substrate, a first electrode formed on a first surface of the dielectric substrate and having a first opening, a second electrode formed on a second surface of the dielectric substrate and having a second opening, a first conductor plate disposed by being spaced apart from the dielectric substrate by a predetermined distance, and a second conductor plate disposed by being spaced apart from the dielectric substrate by a predetermined distance. The region of the dielectric substrate defined between the first and second electrodes, a free space defined between the first electrode and the first conductor plate and another free space defined between the second electrode and the second conductor plate are cut-off regions for attenuating a high-frequency signal having the same frequency as the resonance frequency.
    Type: Grant
    Filed: March 22, 1996
    Date of Patent: June 9, 1998
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Yohei Ishikawa, Toshiro Hiratsuka, Kenichi Iio, Sadao Yamashita
  • Patent number: 5408690
    Abstract: In an antenna supervising apparatus for supplying a multiplexed signal comprised of a plurality of carrier wave signals respectively outputted from a plurality of transmitters through a transmission line to an antenna, a directional coupler detects progressive signals of the multiplexed signal to the antenna and the reflected signals thereof from the antenna, and a band-pass filter respectively filters the progressive signal and the reflected signal of one carrier wave signal preselected among those of the detected multiplexed signal. Further, a detector respectively detects the filtered progressive signal and the filtered reflected signal of the one carrier wave signal, and a micro processing unit calculates a standing wave ratio with respect to the preselected one carrier wave signal based on the detected signals.
    Type: Grant
    Filed: March 11, 1994
    Date of Patent: April 18, 1995
    Assignee: Murata Mfg. Co., Ltd.
    Inventors: Youhei Ishikawa, Sadao Yamashita, Hidekazu Wada
  • Patent number: 5235294
    Abstract: An auto-tuned apparatus for a band-pass filter, wherein, the generated reference signals having the given frequency to be set are mixed with signals to be outputted from the band-pass filter when the reference signals have been inputted to the band-pass filter so as to multiply them for outputting the signals of the multiplied results, the signals of the direct current component from the signals of the multiplied results to be outputted are filtered, and the band-pass filter is controlled so that the center frequencies of the band-pass filter may agree with the frequencies of the reference signal in accordance with the signal of the direct current component to be outputted, whereby the center frequency of the band-pass filter can be adjusted automatically to the desired set value with simple circuit construction and precision better than in the conventional embodiment.
    Type: Grant
    Filed: January 17, 1992
    Date of Patent: August 10, 1993
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Youhei Ishikawa, Hidekazu Wada, Sadao Yamashita, Hiroyuki Kubo
  • Patent number: 4996506
    Abstract: A band elimination filter which includes at least one or more TM-mode dielectric resonators each including a ceramic casing with an electrically conductive film formed over its inner surface or outer surface, and a dielectric column disposed in a cavity in the ceramic casing, and an electrode provided on the ceramic casing, out of contact with the electrically conductive film, with transmission lines being connected to the electrode.
    Type: Grant
    Filed: September 28, 1989
    Date of Patent: February 26, 1991
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Youhei Ishikawa, Toshiro Hiratsuka, Hirotsugu Abe, Hisashi Takagaki, Sadao Yamashita
  • Patent number: 4740765
    Abstract: A dielectric filter includes a single block made of dielectric material having three or more through holes in which an inner conductor is deposited to define three or more dielectric resonators coupled in a cascade manner. A reactance coupling arrangement is provided for coupling two spaced dielectric resonators with at least one dielectric resonator between them being skipped. By selecting the value of the reactance coupling arrangement, it is possible to provide a filter having a frequency characteristic in a desired format, including at least one pole at a selected point in an attenuation region thereof, without any increase in the number of stages of the dielectric resonators.
    Type: Grant
    Filed: September 29, 1986
    Date of Patent: April 26, 1988
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Youhei Ishikawa, Sadao Yamashita, Kikuo Tsunoda, Toshiro Hiratsuka, Kazuyoshi Miyawaki
  • Patent number: 4636759
    Abstract: An improved electrical trap construction for use in a high frequency circuit device, which is so arranged that a coaxial resonator is connected to a core pin of a coaxial connector mounted on a case which contains the device, so that main currents received from a hot signal line flow into or flow out of the coaxial resonator the inner conductive electrode layer of the coaxial resonator is in electrically conducting contact with the core pin of the connector so as to allow the coaxial resonator to provide parallel resonance at a frequency to be trapped.
    Type: Grant
    Filed: March 21, 1985
    Date of Patent: January 13, 1987
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Youhei Ishikawa, Tadahiro Yorita, Sadao Yamashita
  • Patent number: 4223361
    Abstract: A magnetic recording medium improved in durability which comprises a substrate and a magnetic layer of about 1.0 to 10.mu. in thickness comprising magnetic particles and a binder and being formed on the substrate, characterized in that the magnetic layer further comprises (a) a liquid hydrocarbon having a melting or flowing point of about -20.degree. to -60.degree. C. with (b) .alpha.-iron oxide particles having a particle size of 0.5 to 2.mu. and/or (c) a higher fatty acid having a melting point of about 45.degree. C. or higher.
    Type: Grant
    Filed: November 16, 1978
    Date of Patent: September 16, 1980
    Assignee: Hitachi Maxell, Ltd.
    Inventors: Hiroshi Zaitsu, Takashi Yamase, Sadao Yamashita, Kunio Mizushima
  • Patent number: 4151494
    Abstract: The present invention is an electrical filter which includes coaxial resonators, for example, both-end open type 1/2 wave length TEM (transverse electro-magnetic mode) coaxial resonators, each having dielectric material, for example of titanium oxide group, filling the space between an inner conductor and an outer conductor of the resonator for reduction of size and weight of the resonator with optimum quality factor Q and temperature characteristics, while the predetermined number of these coaxial resonators are accommodated in one or more than two bores longitudinally formed in parallel relation to each other in a filter casing of conductive material for coupling the resonators to each other through capacitors.
    Type: Grant
    Filed: January 24, 1977
    Date of Patent: April 24, 1979
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Toshio Nishikawa, Youhei Ishikawa, Sadahiro Tamura, Sadao Yamashita