Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

Interfaces in nanocarbon materials are highly important, as they determine the properties of carbon-based devices. In terms of carrier and thermal transport properties, the interfacial features are often more important than the intrinsic characteristics. Herein, we describe how 1 min Joule annealing of carbon nanotube (CNT) yarns can convert the interfacial amorphous carbon into graphene fragments. After 1 min Joule annealing, we have obtained multiwalled CNT yarns with extremely high Seebeck coefficients (±100 μV/K) and high thermoelectric power factor (400 and 1000 μW/mK2) at room temperature, both with or without polyethylenimine doping. Theoretical simulations and experimental measurements helped to determine the optimal annealing conditions in terms of a rapid transformation of the interfacial amorphous carbon between the bundled CNTs in the yarn into graphene fragments at â¼2000 K. The present approach represents significant progress in energy materials science, as it provides a guiding principle for the design of interfaces in nanocarbon materials with potential applications in energy-harvesting systems.

DOI： 10.1021/acsaem.9b01736

Scopus

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/rws.2018.8304954

researchmap

Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

DOI： 10.1063/1.4986203

researchmap

Language：Japanese  

We investigate the optical magnetometer for AC magnetic fields at several tens of kilohertz. The sensor requires a DC magnetic field to enhance its sensitivity. In this study, at first, we calibrated the signal response of the sensor using coils. The linear response for applied an AC field was obtained, and its sensitivity was 0.4 nT at 20 kHz. Subsequently, signal responses are investigated for comparison with using permanent magnets applying a DC field. The signal intensity was slightly decreased to about 81% by using magnets. These results suggest the possibility of miniaturization and metal-free configuration of the optical magnetometer.

DOI： 10.14923/transcomj.2016PEP0010

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

By atomistic simulation, we investigate an acoustic wave at THz frequencies in nanoscale thin films of aluminum–nitride piezoelectric material. A mode analysis reveals that the thickness longitudinal mode along the [0001] direction exists stably at the atomic level. To control the acoustic wave, we introduce a phononic crystal (PC) structure in the films. We determine the band-gap frequency in the phonon dispersion of the PC structure and confirm via molecular dynamics simulation that the acoustic wave within the band-gap frequency can be confined by a waveguide structure with a PC. The possibility of designing and controlling a THz acoustic wave in a nanoscale thin film with a PC is thereby demonstrated.

DOI： 10.7567/jjap.54.07hb07

CiNii Article

researchmap

Other Link： http://stacks.iop.org/1347-4065/54/i=7S1/a=07HB07?key=crossref.8f2a84b57934c8e893b2c43c68be3386

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.7567/jjap.52.09kf06

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

In this paper, the transducer that is suitable for the ultrasonic wireless power transmission system is discussed. The transducer is designed based on the Mason's equivalent circuit theory, basically. Design parameters of the transducer are optimized for by using the multi physics analysis and developed. As results, it is confirmed that the transmission efficiency is drastically improved to more than 50%. This result suggests that the WPT by acoustic wave is practicable.

DOI： 10.1541/ieejeiss.132.337

CiNii Article

CiNii Books

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes the compact size rectenna using the open ended diamond antenna which is radiation pattern of sharp. This antenna which is fabricated at the planer has same dimension as the patch antenna. In addition,this antenna's half beamwidth is more narrow than the patch antenna. To realize the compact size rectenna,the dimension of the rectification circuit is smaller than the antenna. So the rectification circuit is constructed of the chip device has the 59.5% of conversion efficiency and the dimension of this circuit has 10mm x 10mm at 5.8GHz. The rectenna array which is composed of 2 elements is fabricated, and confirm operating. As a result the output voltage is 117mV at 0.6m, and 69mV at 1.0m.

DOI： 10.1109/EUMC.2009.5295939

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

One-dimensional CRLH transmission lines are aligned to construct two-dimensional medium with imaging capability not found in homogeneous materials. Mimicking electromagnetic field distribution on a surface of the perfect lens, high resolution imaging is demonstrated. Unlike transmission configurations such as in a lens, the imaging operation proposed in this paper is not disturbed by dissipation or index mismatch, leading to wide band operations.

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In recent years, the development of the in-vivo medical devices are remarkable. Generally, in-vivo devices need the internal battery. The life of internal battery is limited, and the maintenance of the battery is necessary.
For overcoming this problem, the ultrasonic wireless power transmission technology is studied. In the past reports, the transducer of ultrasonic wireless power transmission system is not designed for electrical matching with input source, amplifier circuit, and rectification circuit, etc.
In this paper, we propose the efficient ultrasonic wireless power transmission system. For realizing the efficient system, the impedance matching between the input source, amplifier circuit and the ultrasonic transducer is considered. And the optimum position of two transducers necessary for achieving a high transmission efficiency is searched. Moreover, the voltage booster circuit to obtain the high DC oputput voltage is designed. In the transmission experiment, it is confirmed that the high DC output voltage for the operation of the in-vivo devices is achieved.

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：HORIZON HOUSE PUBLICATIONS LTD  

For applications of the microwave power transmission technology, it is necessary to realize high efficiency rectennas or rectification circuits. Especially, RF-ID's or ubiquitous power sources demand high RF-DC conversion efficiency for below, mW microwave inputs. However, almost all past rectennas or rectification circuits were designed for over 100 mW rectifying and the RF-DC conversion efficiencies were less than 20% at 1mW microwave input. In this paper, we investigate rectification circuits for developing mW-class rectennas. Discussing diode mount structures in order to increase the efficiency below 10 mW microwave input, we succeeded in developing a rectification circuit whose efficiency is 62.8% for a 10 mW microwave input. We also find that approximately 30% of the input microwave power is consumed by the diode in the rectification circuit.

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：HARBIN INSTITUTE TECHNOLOGY PUBLISHERS  

Multiple-way power divider/combiner's with a rectangular waveguide port for input/output signal and microstrip line ports for output/input signals are presented. A number of dividing/combining units are successively connected in the chain structure. The unit is composed of the rectangular waveguide section with the microstrip-line probe pair and the thin narrow section. Using as the divider, the chain structure has wideband performance due to the traveling-wave opeartion. High isolation between the paired ports in the unit is established by connecting the paired microstrip lines via a chip resistor. The four-way divider/combiner operating at X-band is designed. The broadband characteristics and. high isolations among the furcated ports are confirmed by the prototype divider/combiner.

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：CITY UNIVERSITY HONG KONG  

In this paper, we conduct propagation measurements focusing on the radiation pattern and the polarization of base station antennas under the line of sight(LOS) and no LOS environments. We measured and investigated propagation characteristics inside them, and we confirmed that propagation characteristics inside passages are depended on its cross sectional shape and that a attenuation coefficient is changed by the radiation pattern and the polarization of the base station antenna.

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：I E E E  

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：I E E E  

Web of Science

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

Language：Japanese   Publisher：電子情報通信学会  

CiNii Article

CiNii Books

J-GLOBAL

researchmap

J-GLOBAL

researchmap

Language：English   Publisher：IEEE  

We demonstrated optical imagings of AC magnetic fields. A digital micro-mirror device and a lock-in detection allowed obtaining sub-millimeter resolution images without using magnetic shields. Images of gradient field from a wire suggested its potential to apply for signal-source estimations.

DOI： 10.23919/MOC.2017.8244562

Web of Science

Scopus

researchmap

Language：Japanese   Publisher：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：WILEY-BLACKWELL  

The lens effect of acoustic waves in a two-dimensional (2D) phononic crystal is studied by numerical simulation based on the finite-difference time-domain (FDTD) method. We calculate the phonon band structure of 2D phononic crystals, consisting of metal/ceramic cylinders placed periodically in water. The lens effect is observed for the far-field wave in phononic crystals with two-layered and graded-index structure. We compare the focal intensity and the energy transmission efficiency in these numerical experiments, and show that a novel energy-transmission device can be designed using phononic crystals. (c) 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 97(1): 22-27, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11491

DOI： 10.1002/ecj.11491

Web of Science

researchmap

researchmap

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Acoustic-wave propagation on silicon surface is studied by numerical simulation based on the molecular dynamics (MD) method. Using a large-scale MD simulation, the present study explores behavior of SAW in Si surface, the influence of anisotropy and reconstruction of the surface, an interaction of the wave with a surface defect, and possibility to realize a filter or a lens effect by an artificial nanostructure formed on the surface.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Using large-scale molecular dynamics simulation, we investigate the stability of screw dislocation in α-alumina. Energies of perfect and partial screw dislocations in α-alumina crystal are compared at several temperatures. In the case of screw dislocation results reveal that perfect dislocation in alumina is more stable than partial dislocations. This result is consistent with the experimental observations in that the screw dislocation in alumina is stable against dissociation into partials. We also evaluate the temperature dependence of rigidity modulus of alumina from the stress-distribution calculations.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

We demonstrate the effectiveness of a hybrid Monte Carlo (MC)/molecular dynamics (MD) method in analysis of grain-boundary segregation, a long-time phenomenon from the atomistic-simulation point of view. The Σ9 coincidence grain boundary of Si crystal is adopted as a testbed for the method. We find an efficient sampling of hopping diffusion of a vacancy in the system can be achieved, while the internal energy evaluated from the MD runs at the same temperature as the MC simulation includes the structural relaxation of the system at the temperature.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

We investigate wave-propagation properties of the phononic structure made of polycarbonate embedded in silica glass. Phonon band and elastic wave propagation are calculated and simulated by the FDTD method. We discuss frequency dependence of the wave-propagation properties in the phononic slab in conjunction with the resonance mode excited in the cylindrical polycarbonate, which can be identified as flat hand character in the phonon band diagram.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：AMER INST PHYSICS  

Broadband dielectric spectra from 10 to 10(14) Hz were acquired for 8 mol. % Y2O3/Yb2O3-stabilized zirconia (8YSZ and 8YbSZ) ceramics that related the dipole and ionic polarization losses to the absorption efficiency of electromagnetic irradiation. For 24 GHz irradiation, 8YSZ exhibited a higher absorption efficiency than 8YbSZ, resulting in a higher dielectric loss. The difference in the dielectric loss was interpreted as the difference in the loss of the dipoles originating from the fluctuations in the defect associations (Y'(Zr)Vo and Yb'(Zr)Vo). (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729147]

DOI： 10.1063/1.4729147

Web of Science

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

The device called Rectenna as an antenna for Receive Antenna of radio electric power transmission is used. The RF-DC conversion circuit of high conversion efficiency which is a component of Rectenna cause wireless power transimission of high transmission efficiency. In this paper, The conversion efficiency analysis of RF-DC conversion circuit in change of component oh the diode are investigated to clarify the characteristic of the diode for obtaining highly efficiency conversion circuit.

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：JAPAN SOC APPLIED PHYSICS  

Complex conductivity wideband spectra from 10(-1) to 10(14) Hz (100 THz) were determined for 8 mol% yttria-stabilized zirconia (8YSZ) and 8 mol% ytterbia-stabilized zirconia (8YbSZ) ceramics. The contributions of electrolyte-electrode interfaces, grain boundaries, intragrain ion-hopping, and optical phonons were quantified to relate the microscopic conduction behavior to the overall conductivity. Intrinsic conductivity was mostly governed by ion-hopping. For both 8YSZ and 8YbSZ, ion-hopping followed the universal dielectric response (UDR) for broadband frequencies except for the phonon dispersion frequencies. The higher overall conductivities of the 8YbSZ ceramics compared to the 8YSZ ones were attributed to differences in the UDR contributions. The dominant factor determining the difference in the intrinsic conductivity in broadband frequencies from direct current (DC) to microwave between the 8YSZ and 8YbSZ ceramics was the DC conductivity due to UDR, sigma(dc), where sigma(dc(8YbSZ)) > sigma(dc(8YSZ)). Other parameters in the UDR and the optical parameters did not greatly influence the intrinsic conductivities. (C) 2012 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.51.011102

Web of Science

researchmap

researchmap

Language：English   Publisher：Institute of Electrical Engineers of Japan  

In this paper, the transducer that is suitable for the ultrasonic wireless power transmission system is discussed. The transducer is designed based on the Mason's equivalent circuit theory, basically. Design parameters of the transducer are optimized for by using the multi physics analysis and developed. As results, it is confirmed that the transmission efficiency is drastically improved to more than 50%. This result suggests that the WPT by acoustic wave is practicable. © 2012 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejeiss.132.337

Scopus

researchmap

Language：English   Publisher：Institute of Electrical Engineers of Japan  

In this paper, the transducer that is suitable for the ultrasonic wireless power transmission system is discussed. The transducer is designed based on the Mason's equivalent circuit theory, basically. Design parameters of the transducer are optimized for by using the multi physics analysis and developed. As results, it is confirmed that the transmission efficiency is drastically improved to more than 50%. This result suggests that the WPT by acoustic wave is practicable. © 2012 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejeiss.132.337

Scopus

researchmap

Language：English   Publisher：Institute of Electrical Engineers of Japan  

Lens effect of acoustic wave in two-dimensional (2D) phononic crystal is studied by numerical simulation based on the finite-difference time-domain (FDTD) method. We calculate the phonon band structure of 2D phononic crystals, consisting of metal/ceramic cylinders placed periodically in water. Lens effect is observed for far-field wave in the phononic crystals with two-layered and graded-index structure. We compare the focal intensity and the energy transmission efficiency in these numerical experiments, and show that a novel energy-transmission device can be designed using phononic crystals. © 2012 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejeiss.132.686

Scopus

researchmap

Language：English   Publisher：Institute of Electrical Engineers of Japan  

Lens effect of acoustic wave in two-dimensional (2D) phononic crystal is studied by numerical simulation based on the finite-difference time-domain (FDTD) method. We calculate the phonon band structure of 2D phononic crystals, consisting of metal/ceramic cylinders placed periodically in water. Lens effect is observed for far-field wave in the phononic crystals with two-layered and graded-index structure. We compare the focal intensity and the energy transmission efficiency in these numerical experiments, and show that a novel energy-transmission device can be designed using phononic crystals. © 2012 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejeiss.132.686

Scopus

researchmap

researchmap

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

Traveling-wave power divider/combiner's adequate for high power amplifying systems have been investigated. Multiple dividing/combiring units are successively connected in the divider/combiner. The unit consists of a rectangular waveguide section with a coaxial probe pair and a thin narrow section. In design of the units based on their equivalent circuit, frequency dependency of the admittance of individual elements in the equivalent circuit was taken into account. In addition, the length of the waveguide between the adjacent units was optimized in order to maximize isolation among the coaxial branch ports in the different units. Bandwidth for dividing power ratios deviation less than ±0.5dB was 3.3GHz, and that for -20dB return loss was wider than 5.7GHz for the designed eight-way divider operated in X-band. Furthermore, the isolation of 18dB among the branch ports was achieved.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Acoustic-wave propagation on semiconductor surface is studied by numerical simulation based on the molecular dynamics (MD) method. We investigate the effect of crystallographic anisotropy, finiteness of thickness of crystal slab, and the presence of defects on the wave propagations. Based on these analyses, we attempt to design atomic-level surface structure of Si for a surface acoustic-wave filter and lenses.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：JAPAN SOC APPLIED PHYSICS  

The negative refraction of acoustic waves in a two-dimensional phononic-crystal slab is studied by numerical simulation based on the finite-difference time-domain (FDTD) method and by ultrasonic measurement. The incident-angle dependences of energy-transmission efficiency in the simulation and experiment are in good agreement in the frequency range of approximately 1.2 MHz. Using the FDTD method, we optimize the efficiency by varying structural parameters such as filling fraction and slab thickness. The effect of deviation from the ideal crystallinity is also evaluated quantitatively via the simulation. These results indicate that an energetically efficient acoustic lens can be fabricated by carefully optimizing the structure of the phononic crystal. (C) 2011 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.50.067301

Web of Science

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：English  

We design and characterize a two-dimensional sonic crystal (SC) to manipulate the propagation of acoustic waves by numerical simulation based on the finite-difference time-domain (FDTD) method and by ultrasonic measurement. Two types of SC for an acoustic lens effect are studied. One is a homogeneous periodic structure exhibiting negative refraction, and the other has a hetero-structure. Negative refraction behavior in the simulation is good agreement with the experiment in the frequency range around 1.2MHz. We also observe a lens effect for far-field wave in the hetero-structured SC. These results indicate that a novel energy-transmission/harvesting device can be designed using SCs. © 2011 IEEE.

DOI： 10.1109/IMWS.2011.5877131

Scopus

researchmap

Language：English  

We developed a fundamental testbed and investigated the suitable transducer for the wireless power transmission (WPT). We also reported experimental results of the transmission efficiency in water by using the commercial transducer (COM) which only designed to match to the acoustic impedance of water and the electric impedance of the transmitter and receiver. In this paper, we investigate the transducer for improving the efficiency based on the Mason's equivalent circuit. For deciding a structure and materials of the transducer, we used ANSYS well-known as the multi-physics simulator. In this result, it is confirmed that the transmission efficiency is drastically improved from less than 1% to 60%. In addition, we made designed transducer, and confirmed the systems' efficiency is about 50 %. This result suggests that the WPT by acoustic wave is practicable. © 2011 IEEE.

DOI： 10.1109/IMWS.2011.5877115

Scopus

researchmap

researchmap

Language：English   Publisher：IEEE  

We developed a fundamental testbed and investigated the suitable transducer for the wireless power transmission (WPT). We also had reported experimental results of the transmission efficiency in water by using the commercial transducer (COM) which only designed to match to the acoustic impedance of water by its structure and the electric impedance of the transmitter and receiver by matching networks. In this paper, we investigate the transducer (DEV) for improving the transmission efficiency based on the Mason's equivalent circuit. For deciding a structure and materials of the transducer, we used ANSYS well-known as the multi-physics simulator.
In this result, it is confirmed that the transmission efficiency is drastically improved from less than 1% to 60% compared to our previous report. In addition, we manufactured designed transducer, and confirmed the system's efficiency is about 50 % experimentally. This result also suggests that WPT by the acoustic wave be practicable.

Web of Science

researchmap

Language：English   Publisher：IEEE  

RF-DC conversion circuit is one of the most important components in the wireless power transmission technologies. For realizing highly efficient wireless power transmission, it is necessary to design the RF-DC conversion circuit with high conversion efficiency, and the designing method of the circuit is actively studied. In this paper, the influences of diode parameters, such as its resistance, junction capacitance, parasitic reactance, and so on, on the conversion efficiency of the RF-DC conversion circuit are investigated to clarify the characteristic of the diode for obtaining highly efficient RF-DC conversion circuit.

Web of Science

researchmap

Language：English  

A Rectifying Antenna (Rectenna) is one of the most important components for a wireless power transmission. It has been developed for many applications such as Space Solar Power System (SSPS), and Radio Frequency Identification (RFID) etc. The Rectenna consisting of RF-DC conversion circuits and receiving antennas needs to be designed for high conversion efficiency to achieve efficient power transmission. we try to design the mw-Class RF-DC conversion circuit using half-and full-wave rectification. The measured conversion efficiencies is 59.3 % and 65.3 % athalf- and full-wave type, respectively. And the full-wave type has lower 2nd harmonic reflection coefficient. © 2011 IEEE.

DOI： 10.1109/IMWS.2011.5877081

Scopus

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

Measurements of scattering parameters of devices with rectangular waveguide ports and coaxial line ports have been investigated. Unknown "thru" calibration was employed for characterizing a transition for converting the coaxial line test port to the waveguide. Transmission phase of the unknown "thru" must be known to within ±90° in the calibration procedure. A transition from the coaxial line to the waveguide used as the unknown "thru" was designed with an electromagnetic field simulator, and simulated values of the transmission phase was adopted as the required known values. The scattering parameters of a waveguide section with a coaxial probe were measured with a fabricated unknown "thru."

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

A rectifying antenna is one of the most important components for wireless power transmission applications. In our previous papers, some RF-DC conversion circuits with high conversion efficiency at low input power are proposed. However, these RF-DC conversion circuits have some parts of which size depends on operating frequency, so the circuit size becomes large at low operating frequency. And, the composition of these RF-DC conversion circuits is complicated. Therefore, in this paper, a new RF-DC conversion circuit composed of only chip devices is proposed. This circuit has higher conversion efficiency than the previously proposed circuits. And, size reduction of the RF-DC conversion circuit is realized. Moreover, the composition of the circuit is simple, so the circuit size does not depend on operating frequency. For design of the RF-DC conversion circuits, LE-FDTD method is used. The measurement results agree with analytical results of the LE-FDTD method very well, and availability of the LE-FDTD method is discovered. It is shown that LE-FDTD method is a powerful analytical way which can give efficient design of RF-DC conversion circuit with high conversion efficiency.

DOI： 10.1587/transele.E93.C.1323

Web of Science

researchmap

researchmap

Language：English   Publisher：IEEE  

For designing a high-efficiency RF DC conversion circuit, simulations and trial and error usually occupy a large part of the work. Such design method needs much time. The important part of design is to design an input circuit. The efficiency of a conversion circuit mainly depends on input circuit. However, it is difficult to design the input circuits. This study takes notice of the voltage when the DC load resistance is open. The open DC load voltage is an important quantity for design of the high-efficiency RF DC conversion circuit. We show by experiments and simulations that the efficiency of an RF DC conversion circuit tends to increase with the open DC load voltage. This relation can make it easier to design RF DC conversion circuit.

Web of Science

researchmap

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：IEEE  

Recently, various wireless applications have hugely become popular. Especially, mobile terminals such as mobile phones are actively developed. In developments of mobile terminals, miniaturization and frequency multiband of antennas are very important issues. However, there are no rational design strategy in small antenna designs. So, antenna developments depends on electromagnetic simulators or capability of engineer. And many cut-and-try processes are necessary for achieving desired characteristic. This makes many problems such as prolongation of developments. Then, now, automatic design techniques of antenna using genetic algorithm (GA) are paid attention.
In this paper, the new design strategy for miniaturization of antennas is proposed by operation of chromosome-length in GA. Proposed design technique provides a minimum area necessary for keeping characteristics of a antenna. And, efficient miniaturization of a antenna and removing many undesirable conductors in a design ares are possible. Removing undesirable conductors provides lower-cost designing of antennas. The new design method can become rational design strategy for antennas miniaturization.

DOI： 10.1109/APMC.2009.5384162

Web of Science

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

Cylindrical power divider/combiner's with broadband coaxial-conical-radial line transition have been studied, which have broadband and low loss characteristics required for the power dividing-combining systems in order to realize microwave high power solid-state amplifiers. The power divider/combiner's is composed of the coaxial-conical-radial line transition as the central part, and the peripheral part in which the coaxial probes are line. In the transition, the coaxial line is converted via two sections of the conical lines to the radial line. The characteristic impedance of the radial line has an imaginary part, and so that the conical line of the second stage is used as a matching line such as the quarter-wavelength transformer. Therefore, the transition can be designed which have lower return loss in the wide frequency range. The validity of the design procedure was confirmed with the experiments for the prototype twelve-way dividers.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

Inverse class-C frequency doubling operation has been discussed for frequency doublers and second harmonic oscillators with high output power and high efficiency. It was demonstrated that high second harmonic output power can be obtained with high drain efficiency higher than 60% when the load whose impedance is infinity at all odd harmonicfrequencies including fundamental frequency and the same resistance at all even harmonic frequencies is used by inverse class-C operation. the drain efficiency higher than 80% can be achieved by the larger input power.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：IEEE  

DOI： 10.1109/APMC.2008.4958657

Web of Science

researchmap

Language：English   Publisher：IEEE  

DOI： 10.1109/APMC.2008.4958300

Web of Science

researchmap

Language：English   Publisher：IEEE  

Transmission line metamaterials based on composite right-left handed (CRLH) structures with pseudoperiodicity are proposed and analyzed experimentally. These metamaterials can be used in various microwave circuits to control not only amplitude but also phase responses of electromagnetic waves. Introducing some kinds of pseudoperiodicity can control phase responses of reflected waves, without affecting severely on electromagnetic bandgap (EBG) properties of periodic structures. Equivalent circuit approaches including distributed line sections are used to design non-periodic structures, resulting in an efficient design procedure. Pseudoperiodic design is also useful for homogenization of conventional metamaterials.

DOI： 10.1109/EUMC.2008.4751685

Web of Science

researchmap

Language：English   Publisher：IEEE  

A Rectifying Antenna (Rectenna) is one of the most important components for a wireless power transmission. It has been developed for many applications such as Space Solar Power System (SSPS), Radio Frequency IDentification (RF-ID), and electric vehicle etc. The Rectenna consisting of RF-DC conversion circuits and receiving antennas needs to be designed for high conversion efficiency to achieve efficient power transmission. In this paper, we investigated the RF-DC conversion circuits by the theoretical analysis. And, we propose the theoretical formula for calculating the output DC voltage in giving the input voltage. The result that is calculated by the formula agreed with the simulator's result, so, we confirmed the validity of the formula we derived. The theory and the formula we derived are useful in order to know the basic operation of the RF-DC conversion circuit, and to design the circuit efficiently.

DOI： 10.1109/EMICC.2008.4772306

Web of Science

researchmap

Language：English   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

The trend of microwave circuits has been toward highly integrated systems. Most design tools for designing microwave circuits mounted the linear or the nonlinear devices adopt the fundamental circuit theory using the S matrix on the frequency domain. The harmonic balance method is also used to correspond to the nonlinear circuit. Therefore, the effect of the electromagnetic field, for example, a mutual coupling between sub-circuits through the, space is almost disregarded. To calculate these circuits included its surrounding electromagnetic field, the finite difference time domain method combined with the equivalent circuit simulation had been presented as the lumped element FDTD (LE-FDTD) method. In general, even if an analytical target is a linear circuit, the FDTD method requires very long analytical time. In this paper, we propose an efficient LE-FDTD method to reduce the analytical time. We investigate its efficiency to compare with the conventional LE-FDTD method or measurements, consequently, it is confirmed that the proposal method requires only at analytical time of 1/10 compared with the conventional method. We also show that the proposal method is able to analyze characteristics of the active integrated antenna (AIA) which are practicably impossible to analyze by using the conventional method.

DOI： 10.1093/ietele/e90-c.9.1776

Web of Science

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

In the second harmonic generation with FETs, optimum configuration of input circuits connected to the gate terminal and output circuits connected to the drain terminal have been investigated. Circuit simulations and experiments of frequency doublers revealed that the input circuits which are conjugately matched with the gate terminal or the fundamental component and has an appropriate reactance at the second harmonic frequency, and the output circuit with the fundamental reactive termination for the inverse class-C operation are required for efficient frequency doubling. By applying the optimum input and output circuits to the single ended second harmonic oscillators, output powers of higher than 20mW and drain efficiencies of higher than 20% were obtained in both cases of the fundamental oscillation frequency of 4GHz and 6GHz.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：IEEE  

A Rectifying Antenna (Rectenna) is one of the most important components for a wireless power transmission. It has been developed for many applications such as Space Solar Power System (SSPS), and Radio Frequency Identification (RFID) etc. The Rectenna consisting of RF-DC conversion circuits and receiving antennas needs to be designed for high conversion efficiency to achieve efficient power transmission. In this paper, we try to design the mw-Class RF-DC conversion circuit using full-wave rectification.

DOI： 10.1109/EUMC.2007.4405340

Web of Science

researchmap

researchmap

Language：English   Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS  

An examination is made of phased array operation, by injecting signals with different phases into both ends of a coupled microwave oscillator system and controlling that phase, as a system for an active phased array antenna using frequency locking. This system has multiple operating modes, but by causing a slight deviation of only the free-running frequency of the end oscillator from the frequency of the injection signal, mode jumps can be suppressed and the phase difference between the oscillators made large. The effectiveness of this method can be numerically confirmed by finding the conditions for single mode operation with an approximation analysis of the governing equation. Using an active integrated antenna constructed of a patch antenna and serial-feedback FET oscillators, an experiment was performed by scanning the radiation beams of two-, three-, and five-element antenna arrays to demonstrate that the scan range in the radiation direction was extended with single mode operation. (C) 2007 Wiley Periodicals, Inc.

DOI： 10.1002/ecjb.20293

Web of Science

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

In order to obtain high output power in higher frequency range such as millimeter wave, an input gate network for second harmonic FET oscillators has been investigated. In the frequency doubler, by using the input network which matches the gate terminal to signal source impedance for fundamental component and has pure reactance at both second and third harmonic frequencies, considerably high output power of second harmonic component was obtained compared with the case using a simple 50Ω line as an input network. The same input network was implemented with the second harmonic oscillator with the fundamental oscillation frequency of 4GHz, and high output power of second harmonic was obtained as 26mW.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS  

In order to make the scanned radiation beam range wider, phased array operation of an active antenna radiating the second harmonic is studied. By numerical analysis of a coupled oscillator system modeling file active antenna array, it is shown that the variation of the phase difference of the second harmonic component between the oscillators reaches 2 pi when the oscillators are coupled only by the fundamental components. This value is twice that yielding the fundamental component. Through experiments using two- and four-element arrays, the results of the analysis are confirmed. The radiation beam of the second harmonic is successfully scanned in a wider range than that for the fundamental component. (c) 2006 Wiley Periodicals, Inc.

DOI： 10.1002/ecjb.20168

Web of Science

researchmap

Language：English  

The trend of microwave circuits has been toward highly integrated systems. Most design tools for circuits are based on the fundamental circuit theory using the S matrix combined with the harmonic-balance method. Consequently, the electromagnetic effect is ignored or approximated at best. Therefore, the extended finite-difference time-domain(FDTD) method combined with the equivalent circuit simulation had been presented. However, it takes very long times to analyze any circuits. In this paper, we propose a novel extended FDTD method to reduce calculation resources. We investigate its efficiency to compare with the conventional extended FDTD method or measurements, consequently, it is confirmed that the proposal method is required calculation resources less than 10% compared with the conventional method. We also show that the proposal method is able to analyze characteristics of the active integrated antenna(AIA) which are practicably impossible to analyze by using the conventional method. Copyright 2006 IEICE.

DOI： 10.1109/APMC.2006.4429570

Scopus

researchmap

Language：English   Publisher：Institute of Electrical and Electronics Engineers Inc.  

A Rectenna is one of the most important components for a wireless power transmission. It has been developed for many applications such as Space Solar Power System (SSPS), and RFID etc. The rectenna consisting of RF-DC conversion circuits and receiving antennas needs to be designed for high conversion efficiency to achieve efficient power transmission. In this paper, the extended FDTD method is proposed as a method for calculating the RF-DC conversion circuit, and the availability of this method is confirmed. Furthermore, the output power from the circuit including the radiation power is investigated. Copyright 2006 IEICE.

DOI： 10.1109/APMC.2006.4429790

Scopus

researchmap

researchmap

researchmap

researchmap

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

In order to realize more miniaturized wireless terminals with multi-function, an active integrated antenna which receives RF signal and down-converts it into IF signal has been investigated. The active antenna consists of a patch antenna and a feedback oscillator operating as a self-oscillating harmonic mixer where the IF is equal to difference between the RF and double of local oscillating (LO) frequency. Characteristics of a used FET were measured so that optimum LO input signal level to the gate and optimum feedback factor in local oscillation with maximum RF-IF conversion efficiency were obtained. By experiments of the self-oscillating mixer with the optimum feedback factor, the maximum conversion efficiency was obtained. In the active integrated antenna with the optimum mixer, high RF-IF conversion efficiency of -0.8dB was achieved.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese  

CiNii Article

CiNii Books

researchmap

Language：Japanese  

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：The Institute of Electronics, Information and Communication Engineers  

Active integrated antenna techniques have high potential for giving smaller size, lighter weight, lower cost and higher efficiency, in particular to millimeter-wave circuit-antenna systems. This paper gives a review of active integrated antenna techniques with emphasis on beam steering and retrodirective antenna arrays. Various beam steering operations of integrated antenna oscillator arrays using locking phenomena are presented. Beam steering arrays of such type have the feature that phase shifters are not necessary in the arrays. Arrays with higher harmonic output radiation can enlarge the beam steering range. Arrays of locked active antennas which operate as self-oscillating mixers can be beam controllable receiving antennas.

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Active integrated antenna techniques have high potential for giving smaller size, lighter weight, lower cost and higher efficiency, in particular to millimeter-wave circuit-antenna systems. This paper gives a review of active integrated antenna techniques with emphasis on beam steering and retrodirective antenna arrays. Various beam steering operations of integrated antenna oscillator arrays using locking phenomena are presented. Beam steering arrays of such type have the feature that phase shifters are not necessary in the arrays. Arrays with higher harmonic output radiation can enlarge the beam steering range. Arrays of locked active antennas which operate as self-oscillating mixers can be beam controllable receiving antennas.

DOI： 10.1093/ietele/e88-c.7.1358

Web of Science

researchmap

Language：English   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Beam control using active antenna arrays with selfoscillating harmonic mixers has been investigated. The active antenna is composed of a patch antenna receiving RF signal and a parallel feedback type oscillator which operates as the self-oscillating harmonic mixer, and down-converts the received RF signal into IF signal. The mixer has two ports for local oscillating (LO) signal. One is an output port extracting the LO signal. The other is an input port for an injection signal to synchronize the local oscillation. The mixers can be coupled unilaterally without other nonreciprocal components by connecting the output port to the input port in the next mixer. In the unilaterally coupled array, the phase differences of the LO signals between the adjacent mixers can be varied without phase shifters in injection locking state by changing the local free-running frequencies of the self-oscillating mixers. The receiving pattern can be controlled by combining the IF signals from the individual active antennas, which have phases associated with the LO signals. The IF is difference between the RF and double of the LO frequency so that arbitrary phase differences from 0 to 2 pi radian can be provided to the output IF signals. The experiments using the two- and three-element arrays demonstrated beam control capability.

DOI： 10.1093/ietele/e88-c.7.1375

Web of Science

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

In order to obtain high output power in higher frequency range such as millimeter wave, optimum fundamental load impedance for second harmonic oscillator has been investigated. First, fundamental load reactance of frequency doublers for maximum second harmonic output power was obtained by an approximated equivalent model for the used FET and experiments of the fabricated doublers. When the second harmonic oscillator with fundamental oscillation frequency of 6GHz had the fundamental load impedance whose the imaginary part was nearly equal to the value for the frequency doubler with the same FET, second harmonic output power and drain efficiency were obtained as 27mW and 26%, respectively.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

The rectangular waveguide chain power divider/combiner with microstrip line probe pairs has been presented. The divider/combiner is composed by connecting successively dividing/combining units each of which consists of microstrip line probes inserted into a rectangular waveguide and a thin narrow waveguide section and has broadband performance. High isolation between the paired branch ports in the unit can be obtained with coupling of the paired microstrip lines via a chip resistor. The experiments at X-band showed wideband dividing characteristics and high isolation among the furcated ports of the prototype four-way divider/combiner.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese  

CiNii Article

CiNii Books

researchmap

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

In this paper, we analize rectification circuit for low power microwave rectenna mounting a shottky diode to use FDTD method, and investigate parameters to archive a high RF-DC conversion efficiency by the voltage waveform and the current distribution. In addition, we confirm the availability of this method by comparing the load voltage obtained by FDTD analysis with the measured result.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

In this paper, we argue about miniaturization of circularly polarized wave patch antenna with cross-shaped slits. By comparing result of analysis to result of experiment, we check the adequacy of FDTD method, and we set up some notches or some cross-shaped slits on the patch antenna to make it small, and we consider miniaturization of circularly polarized wave patch antenna quantitatively by FDTD method. As a result we show 60% miniaturization when we set up four 12mm notches and we show 50% miniaturization when we set up four 12mm cross-shaped slits. Furthermore patch antenna has a high order mode resonance when we set up some notches or cross-shaped slits. We show the factor of this resonance.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

Cylindrical power divider/combiner's with coaxial-conical-radial line transformation have been studied, which have broadband and low loss characteristics required for the power dividing-combining system in order to realize microwave high power solid-state amplifiers. The divider/combiner is composed of the central part in which has coaxial-conical-radial line transformation, and the peripheral part in which the coaxial probes are inserted into the radial line. Each part is designed with the electromagnetic simulator in order to have wide bandwidth. The divider/combiner's are constructed by connecting the optimum central and peripheral parts. In the experiment for the prototype twelve-way divider/combiner, the relative bandwidth, in which the return loss is less than -20dB, was achieved with 68.9%.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

In this paper, we focus attention on the method of numerical simulation directly combining FDTD simulation and circuit simulation, and investigate about characteristics and the calculation procedure to obtain them of low noise microwave amplifier using GaAsFET. We confirm the availability of this simulation method by comparing FDTD results with the results of circuit simulator and measurement. We also investigate about the feeding scheme of DC bias on FDTD simulation and the calculation procedure to obtain S-parameters.

CiNii Article

CiNii Books

researchmap

researchmap

Language：English   Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS  

The measured results and the results of analysis by the ray tracing method in a real tunnel are compared. The propagation characteristics considering the radiation pattern of an antenna placed inside the tunnel are estimated. By comparison of the measured and analyzed results, the effectiveness and validity of the ray tracing method are shown. The propagation loss and fading in the tunnel are discussed. Further, the propagation characteristic is estimated by considering the radiation pattern of the base station antenna for the tunnel booster system. The analysis demonstrates that the dual radiation pattern is effective for the base station antenna. The variation of the covered area when the radiation pattern is varied is studied. (C) 2000 Scripta Technica.

Web of Science

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

In order to realize high speed or capacity telecommunications under the multi-path environment, it is required a progress of S/N. Phased antenna array and adaptive antenna array are used for the purpose to obtain more gain by the control of antenna directivity. In these antennas, it is neccesary that a phase shifter or a function to take the place of it for changing a phase of each element. It this paper, we discuss the 3dB hybrid coupler phase shifter equiped varactor diodes. We also investigated the directivity of the two elements antenna array using this phase sifter.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

The multimedia Mobile Access Communication(MMAC)is reaching for the next generation wireless data transmission system.In this paper, we investigate a bent patch antenna on the rooftop shaped ground plane to obtain same beam width between E- and H-plane for the MMAC base station antenna element.Its base station consists of 3-sector polarization diversity antenna.This paper presents characteristics of a bent patch antenna based on an FDTD simulation results and an example of 3-sector polarization diversity antenna by using a bent patch antenna.

CiNii Article

CiNii Books

researchmap

researchmap

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

In this paper, we investigate the measurement and the processing method for the removal or the decrease of the instability when the measurement system have been received a low input signal. And, the method of averaging measurement samples is proposed, and the influence for the propagation profile or the cumulative probability distribution by this method is examined. In addition, the difference of the propagation profile and the cumulative probability distribution which appears by changing the transmitting power is examined.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

In this paper, we present measurements under street microcell environments by using the bi-directional polarization diversity antenna for the PHS base station, and examine the effectiveness and the validity of the bi-directional radiation pattern. We also examine propagation characteristics due to the radiation pattern and polarization of the base and the mobile station antenna. In addition, we calculate propagation characteristics these environments by the ray tracing method, and discuss differences of propagation characteristics due to radiation patterns and polarizations.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

This paper presents Personal Handy-phone System (PHS) base station placed inside window of building. We measured propagation characteristics by bi-directional polarization diversity antenna as a base station, and investigate influence of glass windows, and the height of base station antenna, effect of polarization diversity.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

In this paper, we present measurements and analyses by the ray tracing method of propagation characteristics in tunnels, and examine the effectiveness and the validity of this analysis method. And, we clarify the effectiveness of the bi-directional antenna for the base station of the booster system, and examine coverage areas by its directivity. In addition, we examine the fading structure in tunnels and effects of the diversity reception of base stations.

CiNii Article

CiNii Books

researchmap

Language：English   Publisher：The Institute of Electronics, Information and Communication Engineers  

In this paper, we present the propagation characteristics inside passages including the radiation pattern and polarization of the base station antenna by experiments. We used passages under the line of sight (LOS) in some buildings for measurements as environments and examined propagation characteristics due to changing the radiation pattern and polarization of base station antenna. And propagation characteristics due to the inclination angle of the mobile station antenna is also examined in consideration of an actual state using of handsets. Then, we clarified the propagation characteristics by changing the radiation pattern and the polarization under the LOS.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

The ray tracing analysis to predict field distributions is presented in this paper. We calculated the propagation characteristics in tunnels, which are veritied by the measurements inside a tunnel. We also calculate field distributions inside the tunnel which was surrounded by a conducting plate partly. Lastly, we investigated the diversity effect in view of the position of the base station.

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

CiNii Article

CiNii Books

researchmap

Event date： 2021.10.23

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.10.23

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2020.12.12

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2020.12.12

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2020.11.28 - 2020.11.29

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2020.10.24

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2020.10.24

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2020.10.24

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2020.10.24

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2019.12.7

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2019.12.7

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2019.12.7

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2019.11.30 - 2019.12.1

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2019.11.30 - 2019.12.1

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2019.11.30 - 2019.12.1

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2019.9.10 - 2019.9.13

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2019.6.10 - 2019.6.11

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2019.3.19 - 2019.3.22

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2018.12.8

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2018.10.20

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2018.10.18 - 2018.10.19

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2018.1.18 - 2018.1.19

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2017.9.22

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2016.3.1

Language：Japanese  

researchmap

Event date： 2016.3.1

Language：Japanese  

researchmap

Event date： 2016.3.1

Language：Japanese  

researchmap

Event date： 2013.3.5

Language：Japanese  

researchmap

Event date： 2013.3.5

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap