bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of piezoelectric transformer using a width‐shear mode
Authors: Wakatsuki Noboru , Ueda Masanori 
Published: July 2007

AbstractAn LiNbO3 single crystal has large electromechanical coupling efficiency, and its elastic loss is small. Using the elastic energy trapping phenomenon of an LiNbO3 single crystal, a piezoelectric transformer can be formed using a width‐shear mode. To reduce the internal loss, a high‐order mode of width vibration is used and multiple pairs of interdigital electrodes formed on the top and bottom surfaces of a piezoelectric substrate are used for both input and output.To analyze the performance of a piezoelectric transformer with interdigital electrodes, Mason's equivalent circuit is used. Finally, the relationship between the designed parameter by the new equivalent circuit and the characteristic of a piezoelectric transformer is investigated to compare the theoretical and experimental results. In particular, it is proved that the ratio of input voltage to output voltage is determined by the load to the transformer and the number of interdigital electrode pairs for the input and output.
Millimeter‐wave active integrated antennas utilizing harmonics
Authors: Kawasaki Shigeo , Itoh Tatsuo 
Published: July 2007

AbstractThis paper reports an active integrated antenna which combines the antenna function with the millimeter‐wave MMIC technology. TJI addition to a high carrier frequency, the compactness of the circuit is extremely useful for applications to automobile radar and wireless LAN.To realize low‐cost millimeter‐wave subsystems, this paper describes an active integrated antenna making use of the slot antenna and the second harmonic of the FET oscillator. The input impedance of the slot antenna is included in the design of a strongly coupled active integrated antenna array. The oscillation frequency of the array was evaluated by a large signal analysis.In the case of a two‐element active integrated antenna using a harmonic, the second harmonic operating frequency of 39.3 GHz was obtained. The phase of the radiation of the fundamental mode was adjusted so that different radiation patterns for different modes were obtained. Also, in the uniplanar‐type four‐element array, a large signal analysis was carried out including the discontinuities in the coplanar waveguide. Through the present trial fabrication, the fundamental data for fabrication of millimeter‐wave monolithic active integrated antennas were obtained.
Design of super wideband electromagnetic wave absorber and its characteristics
Authors: Naito Yoshiyuki , Anzai Hiroki , Mizumoto Tetsuya 
Published: July 2007

AbstractBy combining a ferrite‐type electromagnetic wave absorber and a lossy dielectric layer, an electromagnetic wave absorber with a super wideband characteristic can be realized. In this paper, a grid‐type ferrite absorber and a rubber ferrite loaded ferrite multilayered absorber are treated as a ferrite‐type absorber. When a lossy dielectric material is mounted in front of these ferrite‐type wave absorbers, the thickness of a lossy dielectric layer necessary for realization of a return loss of more than 20 dB at any frequency above 30 MHz was computed. It was found that the thickness is much less than that for the lossy dielectric attached to a single layer ferrite. Further, by means of a model experiment in the coaxial tube, the thickness of the lossy dielectric layer was proven to be smaller if a lossy dielectric is combined with the grid‐type ferrite absorber loaded with rubber ferrite.
Electromagnetic power flow and its expression—poynting vector and Nukiyama vector
Authors: Hosono Toshio 
Published: July 2007

AbstractUsually, the Poynting vector is considered to be a vector field expressing the power flow. However, in many textbooks on electromagnetics the following statements are given which cause confusion: (a) since an arbitrary vector field with zero divergence can be added without violating the energy conservation law, the Poynting vector is not a unique expression for the power flow; and (b) the Poynting vector has nonzero value near a charged magnet. Since it cannot be accepted that a power flow exists in such a space, the Poynting vector may not represent a power flow.Such statements which cause confusion come from the education in which the relativistic aspects of electromagnetic theory have not been considered seriously. This paper is intended to contribute to the electromagnetic education and presents: (a) a clear explanation for the fact that the electromagnetic theory is essentially relativistic; (b) an explanation why the Nukiyama vector does not replace the Poynting vector; (c) general conditions to be satisfied by a vector which can be added to the Poynting vector; and (d) the basis on which we take the Poynting vector as the only expression for the power flow density.
Optical control of active integrated antennas using microwave‐optical interaction
Authors: Kawasaki Shigeo , Itoh Tatsuo 
Published: July 2007

AbstractThis paper reports the optical control of microwave and millimeter‐wave active integrated antennas in which MESFETs are used as the optical control elements. Two types of circuits have been fabricated in which the change of the reactance by the photovoltaic effect of the FET is used. In one of them, the MESFET is used as a passive element which controls the electrical length of the slot antenna by means of the reactance change by optical illumination. It was confirmed that the resonant frequency of this antenna changes by 100 MHz in the × band. In the other circuit, the MESFET used in the oscillator for the active integrated antenna is illuminated optically. An optical tuning range of 63 MHz was observed in the × band. Further, for the latter circuit, a MESFET large signal model was used and the change of the operating frequency was investigated under an assumption of the changes due to optical illumination in the equivalent circuit parameter. It was found that the total of the shifts near the operating frequency of 10 GHz was about 60 MHz if the gate‐source capacitance and the drain‐gate capacitance are increased by 10 percent Hence, these parameters have an important role in the optical control. In addition, an FET structure to obtain a larger optical control range has been studied.
Influence of oxidation of a multilayer metallization on the adhesion of an Sn‐Sb solder
Authors: Kurihara Yasutoshi , Hosokawa Takashi , Saitoh Ryuichi 
Published: July 2007

AbstractThe influence of oxidation of an Al‐Cr‐Ni‐Ag multilayer metallization on the adhesion of Sn‐5wt%Sb solder was investigated. Oxidation of the multilayer metallization prevents the solder from wetting the multilayer metallization uniformly. The nonuniform wetting of the solder caused localization of thermal stress on the wetted regions and promoted differential degradation of the regions.The interface between Ni and Ag was oxidized when exposed to air without cooling to a low temperature. The nickel oxide at the interface prevented the formation of metallurgical bonds between the multilayer metallization and the molten solder. In some interface regions where the molten solder eliminated the nickel oxide either chemically or physically, the solder wetted the multilayer metallization but did not wet in the regions where the nickel oxide was not eliminated.
Study of phase noise reduction in a crystal oscillator circuit with loaded Q
Authors: Sakuta Yukinori , Sasaki Hideki , Hoshino Mitsuharu , Sekine Yoshifumi 
Published: July 2007

AbstractThe paper proposes a new method for improving spectral purity of a crystal oscillator. It is based on the concept that loaded Q can be improved by employing negative resistance circuits. Loaded Q can be higher than unloaded Q of the crystal resonator because the negative resistance circuit compensates losses in feedback circuit of the oscillator. This paper also proposes a new method for evaluation of loaded Q of oscillator circuit. Practical measurement of Q shows that the proposed approach for improving loaded Q leads to better spectral purity of crystal oscillator output.
Spectroscopic measurement of breaking arc light between Ag, Cu, and their combination electrodes
Authors: Kubono Takayoshi , Akaike Tsutomu 
Published: July 2007

AbstractTo investigate the infl uence of electrode material on arc discharge, a dc 30‐V, 3‐ω resistive circuit was interrupted 30 times using an Ag, Cu, or Ag‐Cu combination electrode and the arc duration and optical spectra of light emitted from the arcing area nearby cathode were evaluated. Then, the relationship between the number of breaking operations and arc duration in the breaking arc and that between the number of breaking operations and some kinds of detected spectra and their intensity were investigated.The arc duration was longer when an Ag cathode was used than when a Cu cathode was used. When a Cu anode and Ag cathode combination was used, only the Ag spectrum was observed. When an Ag anode and Cu cathode combination was used, only the Cu spectrum was observed when there were few breaking operations. However, when there were many breaking operations, the Ag spectrum also was observed at the end of arcing. When the number of operations reached 30, the Ag spectrum also was observed at the beginning of arcing and its intensity was high.It is believed that the aforementioned phenomena are due to the vapor pressure difference between two materials, the difference between two breaking arc characteristics, and the volume of transferred material.
Influence of ion bombardment on a‐Si: H films fabricated by plasma chemical vapor deposition
Authors: Kato Isamu , Yoneda Toshiyuki , Matsushita Toru 
Published: July 2007

AbstractPlasma parameters of Ar/SiH4 plasma were measured as a function of dc bias in a double‐tubed coaxial line‐type microwave plasma chemical vapor deposition (CVD) apparatus. The results indicate that it is possible to control the ion bombardment energy without affecting either the gas phase reaction or ion flux density incident to the substrate. Hydrogenated amorphous silicon films were deposited as a function of the ton bombardment energy and characteristics of the deposited films were investigated. The results indicate that the ion bombardment improves film density, bonding characteristics of hydrogen, and optical band gap but increases the concentration of dangling bonds due to Ar ion implantation. The ion bombardment not only causes the heating of the films but also induces sputtering and ion implantation.
An analysis of image‐sticking effect by transmittance drift measurement in liquid crystal cells
Authors: Sasaki Tohru , Tsumura Makoto , Nagae Yoshiharu , Suzuki Masahiko , Iwata Toshiro 
Published: July 2007

AbstractThe image sticking effect in a thin‐film transistor activated liquid crystal display (TFT‐LCD) was related to the transmittance drift caused by dc voltage applied to liquid crystal (LC) cells. Using the electrooptical property of LC, the transmittance drift was calculated based on the drift of the residual dc potential which causes the image sticking effect. The transmittance drift calculated using the experimental result of the residual potential shift agreed with the measured transmittance drift. It was concluded that this calculation method was effective in analyzing the image sticking effect of LC cells.
Approximate analytic equations for small shapiro step Josephson junctions
Authors: Yamaguchi Keiichi , Kawaji Akira , Suzuki Katsumi , Tanaka Syouji 
Published: July 2007

AbstractObservation of Shapiro step is important for evaluation of the Josephson junction. This theoretical characteristic is given by a nonlinear differential equation with the normalized frequency ω based on the current driven resistively shunted junction (RSJ) model as a parameter [14]. Although this model provides good agreement with the experimental results, the number of operations for the numerical solution of the equation is excessive. Hence, discussions of the experimental results by means of theoretical values are difficult. As a result, a proposal of a simple approximate equation which can describe the theoretical characteristics only with ω is considered extremely useful. In the high temperature superconducting junction extensively studied recently, the IcRn product is large and ω < 0.1 is expected. For ω < 0.1, the current amplitude of Shapiro step decreases excessively. In practice, Shapiro steps are often not observed at a high‐temperature superconducting junction. This is considered to be caused by the ω < 0.1 measurement condition. It is important for evaluation of the junction to investigate this problem. No detailed analysis has been carried out for the region with ω < 0.1. On the other hand, since ω < 0.1 is the ideal operating condition of the Josephson mixer, understanding of the characteristics is important from the application point of view. In this paper, understanding of the theoretical characteristics for ω < 0.1, the derivation of the approximate equation and the condition in which Shapiro step cannot be observed are investigated. The analysis results and the experimental values are compared, and the effectiveness of the analysis is presented.
A printed two‐arm spiral antenna operating at the 90‐GHz band
Authors: Fukutomi Toshiyuki , Yasuoka Yoshizumi , Kawasaki Shigeo , Ito Satoshi 
Published: July 2007

AbstractRecently, there has been increased research on millimeter‐wave regions due to mobile communication. In addition to the characteristics of high‐frequency carrier, an even larger‐capacity communication becomes possible by making the communication circuits and the antennas broadband.This paper describes a high‐frequency broadband printed antenna necessary for a monolithic small and lightweight transceiver capable of a large‐capacity communication. As a broadband antenna, a two‐arm spiral antenna was designed and tested at 90 GHz. At frequencies from 89 GHz through 99 GHz, the antenna pattern and the return loss were measured. In addition, Hallen's integral equation for a linear antenna with an arbitrary shape was analyzed numerically by means of the moment method so that the difference between the theory and the measurement was verified. Agreement of both is excellent. Hence, the fundamental data have been collected for realization of broadband active integrated antennas which combine the monolithic circuit and the planar antenna.
Design of receptacle laser diode modules with low reflection
Authors: Shimaoka Makoto , Yagiu Yasutoshi , Kumazawa Tetsuo , Takahashi Syouichi , Sasayama Atsushi 
Published: July 2007

AbstractThis paper describes the configurations and properties of receptacle User diode modules for optical subscriber networks. In optical assemblies where a single mode fiber is coupled using a ball lens, internal reflection frequently takes place. To reduce the back reflection at the fiber end face, a glass plate physically contacted the head of a PC‐polished ferrule. Then the method to evaluate the physical contact between the fiber end face and glass plate was discussed. Inspection with a Newton ring has proved such physical contact to be an efficient method of assembling a glass plate. In addition, modules were fabricated applying the projection and YAG laser welding, both of which are advantageous in firmly coupling components. Then the stability of the output of modules at higher temperatures, the stability of the contact between the module and PC‐FC connector and the influences of temperature cycling and high‐temperature environment on the connector were investigated. It was found that the change in the optical output was small when the temperatures were 0, 25, and 85°C and that the optical output was stable after temperature cycling and a high‐temperature stress test. Therefore, it was concluded that this receptacle laser diode was suitable for the optical subscriber systems.
Analysis of an intersectional optical switch by the finite difference beam propagation method
Authors: Kinoshita Hiroyuki , Kambayashi Toshio 
Published: July 2007

AbstractThree‐dimensional (3‐D) analysis of an intersec‐tional optical switch is performed using the finite difference beam propagation method (FD‐BPM), and design guidelines are obtained from this analysis. The operating characteristics of the switch are evaluated by extinction ratio and power attenuation in two output ports. The optimal structure parameters, such as normalized frequency (V), waveguide relative refractive index difference (Δω), and intersecting angle (θ), are obtained for 1.55 μm wavelength operation. Wideband operation in the 1.3 to 1.6 μm wavelength range is discussed taking into account the wavelength dispersion of materials. It is found that to achieve an extinction ratio that is better than 20 dB, a refractive index variation of 0.5 percent is enough for single‐wavelength operation; however, a refractive index variation larger than 0.7 percent is required at the longer‐wavelength side for wideband operation. Finally, the results of 2‐D and 3‐D analyses are compared and good agreement is obtained with an error of about 1 dB.
Experiments on relationship between metallic phase and gaseous phase arc and contact resistance in ag contacts with opening arc
Authors: Sugimoto Hitoshi , Takagi Tasuku , Sone Hideaki 
Published: July 2007

AbstractTo investigate in detail the relationship between arc duration and contact performance (contact resistance and material wear and transfer) in Ag contacts, arc duration, and contact resistance were measured simultaneously at every contact operation. It has been known that contact resistance is low and stable if arcing continues only in the metallic phase and it is high if the phase is transferred from metallic to gaseous phase during arcing.To investigate the dependence of the arc duration‐contact resistance relationship on the phases, the relationship was evaluated experimentally with various transfer ratios under a constant electrical current of 2.5 to 3.5 A. As a result, it was found that the arc duration was related strongly to the contact resistance immediately after the arc. If the phase did not transfer to the gaseous phase, (he contact resistance was stable and was about 40 mω.Immediately after the transfer to gaseous phase began, the contact resistance increased by 3 to 40 mω. When the arc phase contained gaseous phase, the contact resistance increased by 3 to 10 mω at every operation and finally reached around 100 mω. Then, if arc occurred only in the metallic phase afterward, the contact resistance decreased by 3 to 10 mω at every operation and reached about 40 mω after 10 to 20 operations.
Ferroelectric periodic domain inversion by electron beam writing in optical nonlinear crystal
Authors: Ohashi Motoki , Takyu Choichi , Ito Hiromasa , Taniguchi Hirokazu 
Published: July 2007

AbstractThe quasi‐phase matching (QPM) method is efficient in realizing nonlinear interaction such as second harmonic generation (SHG). In QPM devices, the sign of the nonlinear optical coefficient periodically is inverted. In some methods, the domain structure of ferroelectric material is controlled periodically. The domain inversion can be achieved at room temperature by electron beam writing and electric field application.This paper describes the process to invert periodically the domain structure of LiNbO3 and LiTaO3 by electron beam writing, in particular, the mechanism of the domain inversion due to current absorption on the material surface.
Analysis of and experiment on time response of four‐wave mixing in a photorefractive crystal
Authors: Takayama Yoshihisa , Okamoto Atsushi , Sato Kunihiro , Mishima Teruhito , Sakuraba Ichiro 
Published: July 2007

AbstractTime variations of four‐wave mixing in photore‐fractive crystals is analyzed, and its relation to the physical parameters of the crystal is clarified. Experiments on phase‐conjugate light generation in a BaTiO3 crystal are performed, and the measured data are compared against the results of numerical calculations.Time variations of the coupling coefficient of the photorefractive effect and its relation to the physical parameters of the crystal are derived first and then the phase‐conjugate reflectivity of the transmission‐type diffraction grating is investigated. The pump ratio (the fraction of the forward to the backward pump intensities) and its effects on the time response of the phase‐conjugate reflectivity is for the first time clarified by numerical calculations. Experiments on phase‐conjugate light generation by four‐wave mixing in BaTiO3 are then done and the steady‐state power of the phase‐conjugate light together with the time response to steady state are measured. Finally, the effects of the pump ratio on the phase conjugate power and its time response are compared against experimental data. As a result, it is shown that when the pump ratio is increased nine times, the steady‐state power of the phase‐conjugate light increases approximately 30 times, theoretically, while the measured data indicates an increase that is 24 times. On the other hand, the time response is shown to be delayed four times, theoretically, while the measured value shows a delay of four and a half times. From these results, it is concluded that the time response of the BaTiO3 crystal can be controlled by adjustment of the pump ratio.
Power supply for electroluminescent lamp employing a switched‐capacitor AC‐AC converter
Authors: Oota Ichirou , Ueno Fumio , Harada Ikko , Inoue Takahiro 
Published: July 2007

AbstractA new ac‐ac converter using switched‐capacitor (SC) transformers is presented. The proposed converter is shown to be useful for electroluminescent lamps (EL). The proposed converter has a novel configuration of ac‐ac conversion characterized by the parallel power stage of several SC transformers with 1 : 1 ratio and the unique driving method of switches. The basic operation is described that an ac input voltage is sampled intoncharge‐transfer capacitors by the input‐side switches, and each sampled voltage is selected to the output port by the output‐side switches with an arbitrary frequency. Since the ac input voltage need not convert once to a dc form, the power stage is simple and the efficiency is high. A prototype circuit using five charge‐transfer capacitors (the total capacitance: 149 μF) shows experimentally that it can convert a commercial line voltage (100 V/60 Hz) to a quasi‐sinusoidal wave (400 Hz) with a high efficiency (more than 85 percent) and lighten an EL (size: 1 m2) effectively. The proposed converter can normally supply a power even to an inductive load without a spike noise. The inductance of the smoothing coil can be reduced 1/484 in comparison with the case of a conventional converter with a rectangular output.
Investigation of charge‐trapping centers in low‐pressure chemical vapor deposition Si3N4 thin films
Authors: Minami Shin'Ichi , Kamigaki Yoshiaki 
Published: July 2007

AbstractDefects in Si3N4 films formed by low‐pressure chemical vapor deposition (LPCVD) were investigated by election spin resonance measurement. At room temperature, no electron spin resonance signal was observed in as‐deposited films. When the films were illuminated by ultraviolet ray (UV), signals of dangling bonds of Si (Si‐DB, N3  Si) are detected, where the g‐values were 2.0028 and the half‐value width was 14 G. This means there are N vacancies of weak Si: Si bonds (N3  Si : Si  N3) and/or dipolar‐type defects (N3  Si : Si  N3) caused by redistribution of electrons in N vacancies which cause pairs of defects (N3  Si:−, +Si  N3) by UV illumination. It is proposed that these vacancies can become dipolar‐amphoteric charge‐trapping centers of electrons and holes. The trap density and the charge‐trapping behaviors were investigated by evaluating the characteristics of MNOS nonvolatile memory devices with Si3N4 gate dielectrics.