Patents by Inventor Kunihiro Kawai
Kunihiro Kawai 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).
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Patent number: 7825754Abstract: A variable resonator has a dielectric substrate 2, an input/output line 3 formed on the dielectric substrate 2, a first resonator 4 that has one end connected to the input/output line 3 and the other end grounded, and a second resonator that has one end connected to the input/output line 3 at the point of connection of the one end of the first resonator 4 and the other end grounded via a terminal switch 7. When the terminal switch 7 is turned off, resonance occurs at a frequency at which the sum of the line lengths of the first resonator 4 and the second resonator 6 equals to a quarter of the wavelength. When the terminal switch 7 is turned on, resonance occurs at a frequency at which a half of the sum of the line lengths equals to a quarter of the wavelength.Type: GrantFiled: November 1, 2006Date of Patent: November 2, 2010Assignee: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Atsushi Fukuda, Hiroshi Okazaki, Shoichi Narahashi
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Patent number: 7774034Abstract: A signal switching device including a plurality of transmission paths connected to an input path, the signal switching device outputting a signal from the input path through one of the transmission paths, including a first variable impedance unit connected to a first transmission path, the first variable impedance unit including a first section formed from a superconducting material, the first section being set to a non-superconducting state when the signal is to be output through a second transmission path, the first section including a portion of a predetermined length at an input end, the portion having an area of a cross section less than an area of a cross section of the first section at an output end.Type: GrantFiled: March 29, 2007Date of Patent: August 10, 2010Assignee: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Daisuke Koizumi, Kei Satoh, Shoichi Narahashi, Tetsuo Hirota
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Patent number: 7583168Abstract: An object of the present invention is to provide a resonator capable of constituting a variable filter which has a small size, high mass productivity, low loss and high reproducibility of frequency. According to the present invention, a resonator having a line structure formed on a dielectric substrate 2, is reduced in size by providing a counter electrode 6 in the direction perpendicular to a surface of a resonant line 4 for forming a capacitive reactance which is added to the resonance circuit. The resonator can be further reduced in size by providing widened parts 7a, 7b on the resonant line with the use of the skin effect of an electric signal propagating in the resonant line, so as to enable a large capacitive reactance to be obtained, and by providing the widened parts and the counter electrodes for a part on the resonant line where a magnitude of voltage standing wave is high.Type: GrantFiled: October 7, 2005Date of Patent: September 1, 2009Assignee: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Hiroshi Okazaki, Shoichi Narahashi
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Patent number: 7573356Abstract: A tunable filter wherein coupling sections (51, 52, 53) are formed in an input/output line along its lengthwise direction, each coupling section including a gap (G51, G52, G53) formed in the input/output line and coupling electrodes (E5a1, E5b1, E5c1) arranged in the gap in the longitudinal direction of the input/output line; and resonators (41, 42) capable of varying the resonance frequency are connected to the input/output line at the positions between adjacent ones of the coupling sections. Switch means (71, 72, 73) are provided for selectively grounding the coupling electrodes of the coupling sections or selectively short-circuiting the coupling electrodes and the input/output line, and resonance frequency varying means (4m1, 4m2) are provided for varying the resonance frequency of the one or more resonators in association with the switch means.Type: GrantFiled: February 22, 2007Date of Patent: August 11, 2009Assignee: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Hiroshi Okazaki, Shoichi Narahashi
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Publication number: 20090121803Abstract: A duplexer according to the present invention includes a first port, a second port and a third port for external input/output, a first path formed between the first port and the third port, a second path formed between the second port and the third port, a phase shifting part provided for each path, and a resonating part provided for each path. At least any of the resonating parts has a ring conductor having a length equal to one wavelength at a resonant frequency or an integral multiple thereof, a plurality of passive circuits, and a plurality of switches each of which is connected to a different part of the ring conductor at one end and to any of the passive circuits at the other end. A switch may simply be connected to a ground conductor instead of being connected to the passive circuit.Type: ApplicationFiled: October 28, 2008Publication date: May 14, 2009Applicant: NTT DoCoMo, Inc.Inventors: Kunihiro KAWAI, Hiroshi Okazaki, Shoichi Narahashi
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Publication number: 20090066443Abstract: A signal selecting device according to the present invention has two input/output ports, a plurality of resonating parts, a plurality of impedance transforming parts, and a controlling part. The resonating parts have a ring conductor having a length equal to one wavelength at a resonant frequency or an integral multiple thereof and a plurality of switches each of which is connected to a different part of the ring conductor at one end and to a ground conductor at the other end. The controlling part controls the state of the switches. The resonating parts are disposed in series between the two input/output ports. The impedance transforming parts are disposed between the input/output ports in such a manner that the impedance transforming parts at the both ends are disposed between the input/output port and the resonating part and the remaining impedance transforming parts are disposed between the resonating parts.Type: ApplicationFiled: September 9, 2008Publication date: March 12, 2009Applicant: NTT DoCoMo, IncInventors: Kunihiro KAWAI, Kei Satoh, Hiroshi Okazaki, Shoichi Narahashi
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Publication number: 20080204168Abstract: A variable resonator that comprises a loop line (902) to which two or more switches (903) are connected and N variable reactance means (102) (N?3), in which switches (903) are severally connected to different positions on the loop line (902), the other ends of the switches are severally connected to a ground conductor, and the switches are capable of switching electrical connection/non-connection between the ground conductor and the loop line (902), the variable reactance blocks (102) are severally settable to the same reactance value, and the variable reactance blocks (102) are electrically connected to the loop line (902) as branching circuits along the circumference direction of the loop line (902) at equal electrical length intervals.Type: ApplicationFiled: February 21, 2008Publication date: August 28, 2008Applicant: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Hiroshi Okazaki, Shoichi Narahashi
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Publication number: 20080204169Abstract: A variable resonator that comprises a loop line (902) to which two or more switches (903) are connected and N of reactance circuits (102) (N?3), in which switches (903) are severally connected to different positions on the loop line (902), the other ends of the switches are severally connected to a ground conductor, and the switches are capable of switching electrical connection/non-connection between the ground conductor and the loop line (902), the reactance circuits (102) severally have the same reactance value, the loop line (902) has a circumference corresponding to one wavelength or integral multiple thereof at a resonance frequency corresponding to each reactance value of each reactance circuit, and the reactance circuits (102) are electrically connected to the loop line (902) as branching circuits along the circumference direction of the loop line (902) at equal electrical length intervals.Type: ApplicationFiled: February 21, 2008Publication date: August 28, 2008Applicant: NTT DoCoMo, IncInventors: Kunihiro KAWAI, Hiroshi Okazaki, Shoichi Narahashi
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Publication number: 20080061909Abstract: A variable resonator includes a ring-shaped conductor line (2) which is provided on a dielectric substrate (5) and has a circumferential length of a wavelength at a resonance frequency or an integral multiple of the wavelength, and at least two circuit switches (31, 32), wherein the circuit switches (31, 32) have one ends (31) electrically connected to the ring-shaped conductor line (2) and the other ends (32) electrically connected to a ground conductor (4) formed on the dielectric substrate (5), electrical connection/disconnection between the ground conductor (4) and ring-shaped conductor line (2) can be switched, and the one ends (31) of the circuit switches (31, 32) are connected to the ring-shaped conductor line (2) on different portions.Type: ApplicationFiled: September 7, 2007Publication date: March 13, 2008Applicant: NTT DoCoMo, Inc.Inventors: Kunihiro KAWAI, Hiroshi Okazaki, Shoichi Narahashi
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Patent number: 7307045Abstract: A signal switching device is disclosed that is capable of transmitting signals with less signal loss while securing a good isolation characteristic. The signal switching device includes a first section formed from a superconducting material connected to a first transmission path. The first section has a smaller cross section at the input end than at the output end or, the signal switching device may include a first section formed from a superconducting material connected to a first transmission path in series, and a second section formed from a superconducting material connected to a second transmission path in parallel. The cross section of the second section is smaller than that of the second transmission path. The length of the second transmission path is determined in such a way that an input impedance of the second transmission path is sufficiently large when the second section is in a superconducting state.Type: GrantFiled: November 7, 2003Date of Patent: December 11, 2007Assignee: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Daisuke Koizumi, Kei Satoh, Shoichi Narahashi, Tetsuo Hirota
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Patent number: 7292124Abstract: A variable resonator is provided which comprises signal conductor 13 formed on top side surface of dielectric substrate 12, ground conductor layer 11 formed on back side surface thereof and switches 14, wherein signal conductor comprises a plurality of first conductor lines 13-1 and second conductor line 13-2 connected with all of first conductor lines, each first conductor line has a width larger than that of second conductor line to thereby a signal path through which high-frequency electric signal passes and which is longer than length of second conductor line is provided, switches 14 are connected to the ends of first conductor lines, whereby selectively opening and closing switches will electrically disconnect and interconnect interspaces between ends of first conductor lines to thereby vary length of signal path and thus change resonance frequency.Type: GrantFiled: February 1, 2005Date of Patent: November 6, 2007Assignee: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Daisuke Koizumi, Hiroshi Okazaki, Shoichi Narahashi, Yasushi Yamao
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Publication number: 20070230450Abstract: A signal switching device including a plurality of transmission paths connected to an input path, the signal switching device outputting a signal from the input path through one of the transmission paths, including a first variable impedance unit connected to a first transmission path, the first variable impedance unit including a first section formed from a superconducting material, the first section being set to a non-superconducting state when the signal is to be output through a second transmission path, the first section including a portion of a predetermined length at an input end, the portion having an area of a cross section less than an area of a cross section of the first section at an output end.Type: ApplicationFiled: March 29, 2007Publication date: October 4, 2007Applicant: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Daisuke Koizumi, Kei Satoh, Shoichi Narahashi, Tetsuo Hirota
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Publication number: 20070200651Abstract: A tunable filter wherein coupling sections (51, 52, 53) are formed in an input/output line along its lengthwise direction, each coupling section including a gap (G51, G52, G53) formed in the input/output line and coupling electrodes (E5a1, E5b1, E5c1) arranged in the gap in the longitudinal direction of the input/output line; and resonators (41, 42) capable of varying the resonance frequency are connected to the input/output line at the positions between adjacent ones of the coupling sections. Switch means (71, 72, 73) are provided for selectively grounding the coupling electrodes of the coupling sections or selectively short-circuiting the coupling electrodes and the input/output line, and resonance frequency varying means (4m1, 4m2) are provided for varying the resonance frequency of the one or more resonators in association with the switch means.Type: ApplicationFiled: February 22, 2007Publication date: August 30, 2007Applicant: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Hiroshi Okazaki, Shoichi Narahashi
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Publication number: 20070103261Abstract: A variable resonator has a dielectric substrate 2, an input/output line 3 formed on the dielectric substrate 2, a first resonator 4 that has one end connected to the input/output line 3 and the other end grounded, and a second resonator that has one end connected to the input/output line 3 at the point of connection of the one end of the first resonator 4 and the other end grounded via a terminal switch 7. When the terminal switch 7 is turned off, resonance occurs at a frequency at which the sum of the line lengths of the first resonator 4 and the second resonator 6 equals to a quarter of the wavelength. When the terminal switch 7 is turned on, resonance occurs at a frequency at which a half of the sum of the line lengths equals to a quarter of the wavelength.Type: ApplicationFiled: November 1, 2006Publication date: May 10, 2007Applicant: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Atsushi Fukuda, Hiroshi Okazaki, Shoichi Narahashi
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Publication number: 20060087388Abstract: An object of the present invention is to provide a resonator capable of constituting a variable filter which has a small size, high mass productivity, low loss and high reproducibility of frequency. According to the present invention, a resonator having a line structure formed on a dielectric substrate 2, is reduced in size by providing a counter electrode 6 in the direction perpendicular to a surface of a resonant line 4 for forming a capacitive reactance which is added to the resonance circuit. The resonator can be further reduced in size by providing widened parts 7a, 7b on the resonant line with the use of the skin effect of an electric signal propagating in the resonant line, so as to enable a large capacitive reactance to be obtained, and by providing the widened parts and the counter electrodes for a part on the resonant line where a magnitude of voltage standing wave is high.Type: ApplicationFiled: October 7, 2005Publication date: April 27, 2006Applicant: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Hiroshi Okazaki, Shoichi Narahashi
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Patent number: 6963758Abstract: In a high sensitive radio receiver system for a diversity reception from two antennae per each of three sectors (SC1, SC3, SC3), a series connection of a bandpass filter (31 to 36) and a low noise amplifier (41 to 46) is contained in each of a plurality of vacuum chambers (81 to 86), the interior of which is cooled by a distinct, separate cooling unit (91 to 96). The two antennae per sector are connected to bandpass filters contained in different vacuum chambers.Type: GrantFiled: October 1, 2001Date of Patent: November 8, 2005Assignee: NTT DoCoMo, Inc.Inventors: Shoichi Narahashi, Kunihiro Kawai, Kei Satoh, Toshio Nojima
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Publication number: 20050190018Abstract: A variable resonator is provided which comprises signal conductor 13 formed on top side surface of dielectric substrate 12, ground conductor layer 11 formed on back side surface thereof and switches 14, wherein signal conductor comprises a plurality of first conductor lines 13-1 and second conductor line 13-2 connected with all of first conductor lines, each first conductor line has a width larger than that of second conductor line to thereby a signal path through which high-frequency electric signal passes and which is longer than length of second conductor line is provided, switches 14 are connected to the ends of first conductor lines, whereby selectively opening and closing switches will electrically disconnect and interconnect interspaces between ends of first conductor lines to thereby vary length of signal path and thus change resonance frequency.Type: ApplicationFiled: February 1, 2005Publication date: September 1, 2005Applicant: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Daisuke Koizumi, Hiroshi Okazaki, Shoichi Narahashi, Yasushi Yamao
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Publication number: 20040097379Abstract: A signal switching device is disclosed that is capable of transmitting signals with less signal loss while securing a good isolation characteristic. The signal switching device includes a first section formed from a superconducting material connected to a first transmission path. The first section has a smaller cross section at the input end than at the output end or, the signal switching device may include a first section formed from a superconducting material connected to a first transmission path in series, and a second section formed from a superconducting material connected to a second transmission path in parallel. The cross section of the second section is smaller than that of the second transmission path. The length of the second transmission path is determined in such a way that an input impedance of the second transmission path is sufficiently large when the second section is in a superconducting state.Type: ApplicationFiled: November 7, 2003Publication date: May 20, 2004Applicant: NTT DoCoMo, Inc.Inventors: Kunihiro Kawai, Daisuke Koizumi, Kei Satoh, Shoichi Narahashi, Tetsuo Hirota
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Publication number: 20020173343Abstract: In a high sensitive radio receiver system for a diversity reception from two antennae per each of three sectors (SC1, SC3, SC3), a series connection of a bandpass filter (31 to 36) and a low noise amplifier (41 to 46) is contained in each of a plurality of vacuum chambers (81 to 86), the interior of which is cooled by a distinct, separate cooling unit (91 to 96). The two antennae per sector are connected to bandpass filters contained in different vacuum chambers.Type: ApplicationFiled: May 28, 2002Publication date: November 21, 2002Inventors: Shoichi Narahashi, Kunihiro Kawai, Kei Satoh, Toshio Nojima