健一 石塚

Bio: 健一 石塚 is an academic researcher. The author has contributed to research in topics: Antenna (radio) & Electrical impedance. The author has an hindex of 6, co-authored 24 publications receiving 131 citations.

Antenna and radio communication device

Abstract: PROBLEM TO BE SOLVED: To provide an antenna and a radio communication device which allow complex resonance and have a short antenna length and are capable of controlling a desired resonance frequency without influencing other resonance frequencies. SOLUTION: An antenna 1 includes a radiation electrode 2 for use in a UHF band of high frequencies and an additional radiation electrode 3 for use in a RF-ID band, a FM band, a VHF band, etc. of low frequencies. The additional radiation electrode 3 is branched from the radiation electrode 2 through an inductor 4 and has a front end grounded to a ground area 102 through a reactance varying circuit 5. The inductor 4 is a choke coil which has high impedance at frequencies higher than frequencies in the UHF band. The reactance varying circuit 5 is capable of controlling a resonance frequency of an additional antenna part 6 including the additional radiation electrode 3. COPYRIGHT: (C)2007,JPO&INPIT

Antenna device and communication terminal unit

Abstract: PROBLEM TO BE SOLVED: To form an antenna device which matches impedance with a feeder circuit in a wide frequency band and a communication terminal unit including the antenna device.SOLUTION: An antenna device 106 includes an antenna element 11 and an impedance conversion circuit 25 connecting to the antenna element 11. The impedance conversion circuit 25 connects with a feeding end of the antenna element 11. The impedance conversion circuit 25 is disposed between the antenna element 11 and a feeder circuit 30. The impedance conversion circuit 25 includes a first inductance element L1 connecting to the feeder circuit 30 and a second inductance element L2 connecting to the first inductance element L1, and a first end and a second end of the first inductance element L1 are respectively connected to the feeder circuit 30 and an antenna. A first end and a second end of the second inductance element L2 are respectively connected to the antenna element 11 and a ground.

Frequency stabilization circuit, antenna apparatus, and communication terminal device

Abstract: PROBLEM TO BE SOLVED: To constitute a frequency stabilization circuit capable of stabilizing the frequency of a high frequency signal without being influenced by the form of a radiator and an enclosure, and an arrangement situation of an adjacent component, and to constitute an antenna apparatus and a communication terminal device.SOLUTION: In a frequency stabilization circuit 25 having four coil-like conductors L1 to L4, a first coil-like conductor L1 and a second coil-like conductor L2 are connected in series to constitute a first series circuit, a third coil-like conductor L3 and a fourth coil-like conductor L4 are connected in series to constitute a second series circuit, the first series circuit is connected between an antenna port and a feed port, and the second series circuit is connected between the antenna port and a ground. The first coil-like conductor L1 and the second coil-like conductor L2 are wound so that a first closed magnetic path (a loop shown by magnetic flux FP12) may be constituted, and the third coil-like conductor L3 and the fourth coil-like conductor L4 are wound so that a second magnetic path (a loop shown by magnetic flux FP34) may be constituted.

High frequency transformer, electronic circuit and electronic apparatus

Abstract: PROBLEM TO BE SOLVED: To configure a transformer with high coupling degree which is easily manufactured and downsized and can transfer energy with low loss.SOLUTION: A transformer with high coupling degree 35 is connected between an antenna element 11 and a feeder circuit 30. The transformer with high coupling degree 35 comprises a first inductance element L1 connected to the feeder circuit 30, and a second inductance element L2 coupled with the first inductance element L1. A first end of the first inductance element L1 is connected to the feeder circuit 30 while a second end thereof to the antenna element 11, respectively, and a first end of the second inductance element L2 is connected to the antenna element 11 while a second end thereof to the ground, respectively.

Antenna device and wireless communications equipment

Abstract: PROBLEM TO BE SOLVED: To provide an antenna device which is small and in which broad banding is possible, and to provide wireless communications equipment. SOLUTION: The antenna device 1 is provided with a radiation electrode 2, a radiation electrode 3, a switch 4 and a reactance circuit 5-1. The radiation electrode 2 has a U-shape and is connected to a power feeding part 110. The radiation electrode 3 is disposed inside the radiation electrode 2 and extends, in parallel with an opposite portion 22 of the radiation electrode 2 in close proximity. A distributed constant-type capacitance C is formed between the radiation electrodes 2 and 3 to capacitively couple the radiation electrodes 2 and 3. The switch 4 is an element for electrically connecting or disconnecting the radiation electrode 3 to/from the radiation electrode 2, and the reactance circuit 5-1 is loaded between the switch 4 and the radiation electrode 3, to change the electrical length of the antenna device 1 and consequently, the antenna device 1 resonates at a single-resonance frequency f0, when the switch 4 is off, and is in a double-resonance state of resonance frequencies f1 and f2, when the switch is switched on. COPYRIGHT: (C)2010,JPO&INPIT

Selective specific absorption rate adjustment

Abstract: An electronic device provides a capability of distinguishing between human tissue and a non-human object in proximity of a transmission source. In this manner, transmission power adjustments to the transmission source can be made selectively, depending on whether human tissue or a non-human object is detected in the proximity of the RF transmitter. Distinguishing between human tissue and other non-human-tissue objects in proximity of the transmission source provides for selective control of SAR adjustments. Accordingly, an electronic device can avoid certain communication performance reductions introduced by decreases in transmission power effected to comply with SAR standards by reducing transmission power when human tissue is detected in the proximity but not reducing transmission power when a non-human object (but no human tissue) is detected in the proximity.

Antenna device and communication terminal apparatus

Abstract: An antenna device includes an antenna coil including a first conductive pattern disposed on a first major surface of a magnetic sheet, a second conductive pattern disposed on a first major surface of a non-magnetic sheet, and an interlayer conductor connecting the first conductive pattern and second conductive pattern. The antenna coil including the first conductive pattern and second conductive pattern defines a spiral or substantially spiral pattern. The antenna device is a resin multilayer structure in which its base body is a laminate of the magnetic layer and non-magnetic layer and the predetermined patterns are disposed inside and outside the laminate.

Antenna device and communication terminal device

Abstract: An antenna device includes a first conductor plane and a second conductor plane that face each other. The first conductor plane and the second conductor plane are electrically continuous through a first connection conductor, a second connection conductor, and a chip capacitor. A power feed coil is disposed between the first conductor plane and the second conductor plane. The power feed coil includes a magnetic core and a coil conductor. The coil conductor defines a pattern such that the coil conductor winds around the magnetic core. The power feed coil is disposed at a position closer to the first connection conductor and magnetically couples with the first connection conductor.

Antenna and radio communication apparatus

Abstract: An antenna includes a first arm whose one end is connected to a feeding unit, a second arm whose one end is connected to the first arm at a position that is away from the one end of the first arm and whose other end is connected to ground, and a variable impedance unit whose impedance is variable, provided between the ground and the other end of the first arm.

Antenna device and radio communication device

Abstract: An antenna device capable of not only achieving multiple resonances and wideband characteristics but also achieving improvement of antenna efficiency and accurate matching at all resonant frequencies, and a wireless communication apparatus are provided. An antenna device 1 includes a radiation electrode 2 to which power is capacitively fed through a capacitor portion C1, and additional radiation electrodes 3-1 to 3-3 branched from the radiation electrode 2. A distal end portion 2a of the radiation electrode 2 is grounded to a ground region 402, and is a portion at which a minimum voltage is obtained when power is fed. A capacitor portion C2 that is a portion at which a maximum voltage is obtained when power is fed is disposed in a proximal end portion 2b of the radiation electrode 2, and a variable capacitance element 4 which is grounded is connected in series with the capacitor portion C2. The additional radiation electrodes 3-1 to 3-3 are connected to the radiation electrode 2 through switch elements 31 to 33, and includes reactance circuits 5-1 to 5-3 in a middle thereof. Distal end portions of the additional radiation electrodes 3-1 to 3-3 are grounded to the ground region 402.