bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical control of active integrated antennas using microwave‐optical interaction
Authors: Kawasaki Shigeo , Itoh Tatsuo
Published: July 2007

This 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

The 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

The 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

To 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

Plasma 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

The 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

Observation 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

Recently, 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

This 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

Three‐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

To 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

The 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

Time 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

A 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

Defects 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.
Parallaxless input‐integrated flat panel display
Authors: Miura Masaki , Syoujima Hiroshi , Fukunaga Yasushi , Kondo Katsumi
Published: July 2007

Input‐integrated displays with a tablet and liquid‐crystal display (LCD) have been developed for computers. In the input‐integrated displays, parallax due to the thickness of a glass causes the difference between the positions of a pen and the displayed image.

To eliminate the parallax problem, a fiber plate was used for the upper substrate of an LCD instead of a conventional glass plate and the newly developed LCD was evaluated.

(1) It was found that when a fiber glass was used for the upper substrate of the LCD and liquid‐crystal material with a polarization characteristic (for example, one with dichromatic coloring matter which has anisotropic characteristics in the absorption of visible light in the long and short axes directions of liquid‐crystal molecules), the parallax observed when a glass plate was used almost disappeared.

(2) The relationship among the pen position, glass plate thickness, and dot‐pitch of an LCD for conventional LCDs was obtained. Using the relationship, it was clarified that the disturbance due to the parallax could be eliminated.
Measuring system of A, B, and C photoresist parameters
Authors: Sekiguchi Atsushi , Minami Youichi , Matsuzawa Toshiharu , Takezawa Toru , Miyakawa Hisayuki
Published: July 2007

The concept of parameters A, B, and C of photo resist and outline of measuring theory and an instrument have been reported by Dill et al. in 1975. Since then, parameters A, B, and C have been used in simulation of profile or quality control of photoresist. In practice, however, a dedicated measuring instrument is hardly used and parameters are calculated from transmittance measured with a spectrophotometer instead.

Dill et al. used a substrate of matched refractive index, but quartz substrate without matching its refractive index to photoresist usually is employed for convenience reasons. In this paper, experiments have been made to clarify the difference between Dill's authentic method and conventional method using a newly developed instrument (ABC‐Analyzer) and a conventional spectrophotometer.

Light of broad band from an Xe‐Hg lamp was filtered through a narrow bandpass filter and exposed to a photoresist‐coated sample. Then temporal change of transmittance was measured and stored in a computer. Parameters A, B, and C were determined automatically according to Dill's model using the transmittance data.

Calculated parameters through two different procedures were compared. Parameters A, B, and C obtained by using the developed instrument were lower than those obtained by using a spectrophotometer. The difference comes from the difference in calculation method for transmittance. In other words, the transmittance measured with spectrophotometer is different from that based on Dill's definition.

Furthermore, maximum differences in parameters A and B were 5 and 45 percent, respectively, between those obtained from the samples using an unmatched quartz substrate and a refractive index matched substrate. This is caused by multiple interference between reflected light from the photoresist/substrate interface and that from the back side of the substrate. It was confirmed that it is important to minimize this effect in order to improve accuracy in measuring A, B, and C.
Fabrication of silica‐based optical waveguides with smooth side walls by RF‐bias sputtering
Authors: Akiba Kenji , Takegata Norihiko , Kawakami Shojiro , Shiraishi Kazuo
Published: July 2007

A detailed discussion of the preparation of a buried silica‐based optical waveguide by sputtering is presented. The morphological evolution of SiO2 deposited on a ridge structure and smoothing the side wall are discussed on the basis of both experimental and computer simulation results. A new method of fabricating silica‐based optical waveguides with smooth side walls by radio‐frequency (rf) sputtering is described. A waveguide of either triangular or trapezium‐shaped cross section is fabricated on a prepared ridge in the substrate by rf sputtering. An analysis of the waveguide thus obtained of a triangular‐shaped cross section is made by the propagating beam method (PBM). The potential for application of the technique to optical waveguides is examined.
Frequency stabilization of NRD waveguide gunn oscillator at 60 GHz
Authors: Suzuki Yoshinori , Kuroki Futoshi , Yoneyama Tsukasa
Published: July 2007

Frequency stability of a 60‐GHz nonradiative dielectric (NRD) waveguide InP Gunn diode oscillator has been improved based on the phase‐locked‐loop technique. All the millimeter wave circuit elements needed, including the directional coupler, circulator, and so on, have been fabricated by using the NRD waveguide and a new approach has been introduced for harmonic mixer configuration by combining an NRD waveguide and a laterally shielded coplanar transmission line. By means of this approach, the millimeter wave circuit can be contained in a compact housing of 4 cm × 6 cm in area. The stability of the oscillation frequency of the fabricated Gunn oscillator was 2.1 × 10−10 (13 Hz/60 GHz). Further, the phase noise was kept to a small value of ‐48 dBc/Hz. The present results confirm the applicability of the NRD waveguide in the 60‐GHz band.
Discussions on numerical accuracy of the vector finite element methods using the vector‐shape function
Authors: Ohtaka Masato , Kobayashi Takao
Published: July 2007

With respect to the vector finite element method for analysis of the electromagnetic waveguide, the numerical accuracy and the numerical efficiency are investigated for three types of variational expressions with which spurious‐free vector finite element analyses are possible. For the linear, isotropic, and lossless waveguide, these methods are compared with regard to the physical and mathematical properties and the electromagnetic field construction of the guided mode using vector‐shape functions represented by complete polynomials of identical form. Two of the variational expressions use different‐order shape functions for the two transverse components and the longitudinal component. Four types of computation methods can be constructed by selection of the electromagnetic field components. Another method uses the shape functions with identical orders in four transverse components.

Numerical computations have been carried out for various waveguides. From the results of the computations, it is shown that the physical and mathematical properties of the two variational expressions using the three transverse and longitudinal components are equivalent and that the numerical accuracy of the propagation constant of each guided mode depends on the magnitude of the longitudinal field components used in an actual computation method unlike the method using four transverse components. By using the results, optimum selection of computation methods can be realized.
Analysis of characteristics of a čerenkov laser via particle simulation
Authors: Horinouchi Katsuhiko , Sanda Masaki , Takahashi Hiroyuki , Shiozawa Toshiyuki
Published: July 2007

Using a method for computer simulation, called particle simulation, this paper investigates in detail nonlinear characteristics (whose analytical treatment has been difficult to date) for a Cerenkov laser composed of a parallel plate waveguide loaded with a dielectric sheet and a planar relativistic electron beam focused with infinite magnetostatic field. The main results obtained here are summarized as follows. First, the growth of an electromagnetic wave is found to be due to energy transfer from the kinetic energy of an electron beam to the electromagnetic energy. Initially, the amplitude of an electromagnetic wave grows exponentially, and then nonlinearity gradually begins to dominate as electrons composing the electron beam are trapped in the electric field of the electromagnetic wave. In the final stage where most of the electrons are trapped, the amplitude of the electromagnetic wave gets saturated. In the early stage where the wave amplitude grows exponentially, the results obtained from particle simulation agree well with those obtained from linear analysis. In this paper, the efficiency of energy conversion from the electron beam to the electromagnetic wave is also estimated with the use of the energy carried by the electromagnetic wave at saturation.
Catastrophic optical damage of algalnp visible laser diodes under high‐power operation
Authors: Fukushima Takehiro , Furuya Akira , Kito Yasuhiro , Sudo Hisao , Sugano Mami , Tanahashi Toshiyuki
Published: July 2007

The conventional method to evaluate the lifetime of a laser diode for catastrophic optical damage (COD) has some problems. A new method is proposed that can account for these problems. and the lifetime of AlGalnP visible laser diodes is evaluated using the proposed method. A microauger electron spectroscopy (μ‐AES) is used to analyze quantitatively both the mutual diffusion and the native oxide between the coating film and laser crystal. These effects are clarified on the degradation of COD power level.
Complex permittivity measurements of dielectric plates using a dielectric loaded cavity resonator in UHF band
Authors: Yu Jing , Kobayashi Yoshio
Published: July 2007

A method is proposed for the measurement of complex permittivity (ϵsand tan δs) of a dielectric plate with 50 × 50 mm2at 1 ∼ 2 GHz. A dielectric loaded cavity resonator in which a high permittivity, low‐loss dielectric rod (a relative permittivity of δrand a loss tangent of tan ϵr) is divided into two and a dielectric plate to be measured is inserted between them. The advantage of the present measurement method lies in the fact that the edge effect at the contact planes of the cavity and the sample can be neglected since the energy is concentrated near the dielectric rod. Actually, various plate samples are measured at 2 GHz and the measurement errors are evaluated. For the conventional plate samples with fluctuations in sample thickness 2t= 1.0 mm and the ambiguity Δ2t= 0.01 mm, the measurement accuracy of ϵsis less than 8 percent for ϵs= 2, 3 percent for ϵs= 5, and 2 percent for ϵs= 10. If the manufacturing process allows Δ2t= 0.003 mm, the measurement accuracy of ϵscan be improved to 3 percent, 1 percent, and 0.7 percent, respectively. Also, the measurement accuracy of tan δ is 30 percent for tan δ = 10−4and 2 percent for tan δs= 10−3. The present method is available in the UHF band for the plate samples in the range of ϵs= 2 ∼ 20, tan δ = 10−3∼ 10−4, and 2t= 0.3 ∼ 2 mm.
Design of bandpass filters using triple‐mode dielectric rod resonators
Authors: Komatsu Shigeru , Kobayashi Yoshio
Published: July 2007

Multiply degenerate mode dielectric resonators in which several resonant modes are degenerate in one physical cavity are effective for miniaturizing the bandpass filter (BPF) in the microwave frequencies. In this paper, for a triple‐mode dielectric rod resonator at the resonant frequency of 8.5 GHz at which the TMO1δmode is degenerate with the dual mode EH11δ, an accurate design is carried out. A three‐stage Chebyshev BPF and six‐stage elliptic function BPF are designed using these resonators. The coupling coefficient between the dielectric resonators via a coupling hole is computed by a rigorous electromagnetic field analysis. The validity of the computed results is confirmed by experiment. As a result, in comparison with the BPF using the conventional triple‐mode cylindrical cavity resonators, the filter volume is reduced to one‐fifth.
Lempel‐Ziv‐type high‐speed data compression circuit using content addressable memory
Authors: Satoh Akashi , Niijima Hideto
Published: July 2007

Data compression technology is valuable both for increasing the recording capacity of storage devices and for stepping up the communication speed of networks. The compression algorithm proposed by Lempel and Ziv in 1977 is widely known to give a high compression ratio for data of various types by eliminating repeat data. The drawback of the algorithm is its low speed, which results from the difficulty of searching for variable length repeat data. Content addressable memory (CAM) is effective for increasing search speed, but it is limited to searching for a fixed‐length datum such as a byte or a word.

This paper proposes adding a simple circuit to a CAM, thus allowing it to search for variable‐length data and realizing a very high‐speed data compression circuit.
Low‐voltage, high‐speed, and high‐precision current‐mode sample‐and‐hold circuit
Authors: Sugimoto Yasuhiro , Kakitani Hisao , Tsurumi Hiroyuki
Published: July 2007

The authors investigated the current‐mode sample‐and‐hold circuit with the low‐voltage operation, which can sample and hold the input signal current with a high speed and high precision. The differential amplifier is used as the basic component, and a new circuit configuration is developed where the switches are placed symmetrically at the two input terminals to cancel the clock feedthrough.

The signal dependency is minimized by adequately selecting the current relation in the circuit and the element size. For the realization of the concept described above, two kinds of circuits are prepared. One is the circuit where the input signal current is given in the form of two inputs in differential mode, and the other is the single‐phase, single‐input circuit. By analyzing the proposed circuits using the SPICE circuit simulator, the following current‐mode sample‐and‐hold performances are obtained: 20‐MHz sampling, 40‐MHz bandwidth, linearity within 0.1 percent, and 3‐V operation is obtained for the former, and 20‐MHz sampling, 45‐MHz bandwidth, linearity within 0.1 percent, and 3.5‐V operation is obtained for the latter.

It is seen also that the high‐precision and high‐frequency characteristics, which have been difficult to be made due to the clock feedthrough problem, can now be realized at the same time in the current‐mode circuit.
Automatic on‐line measurement of ship's attitude by use of servo‐type inclinometers
Authors: Member Seiji Nishifuji , Touya Yuji , Tanaka Shogo
Published: July 2007

An accurate measurement of dynamic ship's attitude is important for not only correcting data obtained with sonars in searching seabed patterns but also controlling the attitude of a high‐quality ship. From this viewpoint, a previously developed automatic measurement system measured the heaving, rolling, and pitching of a ship by processing outputs of four servotype accelerome‐ters appropriately located on the ship. However, this measurement system required excessive computational time for data processing because it adopted both the maximum entropy method and an optimization procedure to seek the unknown heaving, rolling, and pitching parameters. To realize the on‐line measurement of the three signals, this paper proposes a new automatic measurement system using two servotype inclinometers and one accelerometer. This measurement system introduces linear dynamic models and linear observation equations on the three signals and reduces the on‐line measurement of the three signals to the state estimation of the linear dynamic systems. A bank of Kalman filters is used to execute the on‐line state estimation and to overcome changes in parameters in the dynamic models with time. Since the proposed measurement system utilizes the two servotype inclinometers and one servotype accelerometer, the measurement system will cost less than the previously proposed one.
A new 8‐12 conversion channel code and its application to high data‐rate video recording
Authors: Ishii Hirotake , Umemoto Masuo , Nonmember Hidehiko Sawamura , Member Yoshizumi Eto
Published: July 2007

Short wavelength recording requires a channel code that has a larger minimum magnetic‐transition interval (Tmin) than the data‐bit interval (Tb). An 8‐12 conversion channel code has been developed in whichTminis 1.33 times longer thanTb. In this code, a maximum of four combinations of 12‐bit channel codes are set for each 8‐bit dataword. The proper channel code is selected by referring to the previous channel code and the tentative next channel code. A word‐inversion scheme can be applied to this conversion channel code, drastically reducing the dc component of the code when the code is used in video‐signal recording. As a result, when recording video signals, the dc component and digital sum variation (DSV) characteristics of the new code are superior to those of the (1, 7)RLL code and similar to those of the NRZ‐ASE code. Simulation showed that the 8‐12 conversion code has superior eye‐pattern and error‐rate characteristics compared to the (1, 7)RLL and NRZ‐ASE codes. A video‐signal recording experiment using the 8‐12 conversion code achieved at a recording rate of 198 Mb/s and a recording density of 5.8 μm2/bit indicates that this code will make HDTV digital video cassette recorders feasible. The experimental average error rate was 7 × 10−5, sufficient for HDTV video recording.
Characteristic analysis and test verification of tapered waveguides with finite wall surface resistance
Authors: Ishihara Fujio
Published: July 2007

The detail behavior of tapered waveguide circuits with finite wall surface resistance used at or close to the cutoff frequency is investigated. The analytical method used is based on a generalized waveguide transmission equation applied to the TE10 mode of a square waveguide with finite inner wall surface resistance. An equation suitable for numerical calculations is derived. Further, in the case of waveguides of finite wall surface resistance, the equivalent characteristic impedance and the propagation constant are also derived. The equations derived herein (imposed to a uniform waveguide) are in agreement with the frequently used approximate equations in the frequency range far from the cutoff. Two types of taper waveguide circuits are devised for uses around the cutoff frequency. The shapes of the measured frequency characteristics of the return losses of these circuits are in agreement with those of the theoretical ones. Further, it is confirmed that if the effective value of the conductivity of the wall surface is taken to be one‐half that of the nominal one, there is good agreement between the theoretical and experimental results.
Improved linear‐approximation of thermoelectric differential equation
Authors: Ogawa Yoshihiko , Kiya Humikazu
Published: July 2007

The differential equation which analyzes the temperature distribution in the thermoelectric device is nonlinear, and we must implement numerical analysis to solve this equation exactly. If we want analytical considerations using the equation, the equation must be transformed into any linear‐approximated differential equation. Before now, we introduced the linearized equation from the exact nonlinear equation under some simple approximation. In this paper, we introduce improved linear‐approximated differential equation under more precise approximation. And analytical results for both linearized methods are compared with the numerical method. As the result, values of temperature distribution, heat‐flow density, and coefficient of performance (COP) of Peltier cooling system obtained by the new linearized method are considerably agreeable with those by the numerical method.
Identification of liquid samples using shear‐horizontal surface acoustic wave sensors
Authors: Kondoh Jun , Shiokawa Showko
Published: July 2007

The shear‐horizontal surface acoustic wave (SH‐SAW) propagating on a piezoelectric crystal is made of a strain wave coupled with a piezoelectric potential due to the piezoelectric effect. Hence, the SH‐SAW can detect not only the effect on the strain but also the phenomena affecting the piezoelectric potential (acousto‐electric interaction). The SH‐type surface acoustic wave on a 36° rotated Y‐cut X‐propagating LiTaO3 is suitable for detection of the electrical properties (relative permittivity and conductivity) of liquid since its large electromechanical coupling coefficient makes the acoustoelectric interaction strong.

In this paper, attention is directed to the frequency dependence of the sensor sensitivity for the acoustoelectric interaction. It is proposed to identify the liquid by means of the sensing system made of several SH‐SAW devices with different frequencies. Specifically, eleven kinds of fruit juice and thirteen kinds of whiskey were identified. It is found that highly accurate distinction can be accomplished without selective organic thin films.
Influence of switching pulse on I‐V characteristics in series‐connected josephson junctions
Authors: Suzuki Hideo , Yoshida Akira
Published: July 2007

To evaluate the scattering in the critical currents of Josephson junctions, the current‐voltage characteristic of series‐connected Josephson devices have usually been evaluated. However, it has been found that the measured current‐voltage characteristics and the number of switched junctions of series‐connected Josephson junctions often depend on the measurement conditions, e.g., the wiring feature.

The authors assumed that these symptoms occurred because the switching pulses generated when the Josephson junctions were switched propagated through the wires serially connecting the junctions and the external wiring circuits. Hence, multiple reflection occurs at the connecting points and terminating points, resulting in a variation in the current flowing through junctions. In the measurement of the current‐voltage characteristics, one of the terminals is grounded inside or outside of the device while the other terminal is connected to a power supply with high impedance.

In this case, when numerous junctions were switched simultaneously, the current‐voltage characteristics depended on the distance between the terminal and grounding point. When the other terminal was terminated with a 50‐ω resistor, the number of junctions which switched simultaneously was small. As a result, it was concluded that the dependence of the current‐voltage characteristics on the measuring methods was due to the multiple reflection of pulses caused when the junction switched.
Millimeter wave mixing in thin‐film YBCO Josephson junctions
Authors: Nozue Takashi , Yasuoka Yoshizumi , Chen Jian , Yamashita Tsutomu
Published: July 2007

Harmonic mixing characteristics were examined in a 94‐GHz millimeter wave region at liquid‐nitrogen temperature (77 K) using thin‐film YBa2Cu3O7 ‐ x (YBCO) Josephson junctions created by laser ablation. As a result, a mixing signal (IF output) with a harmonic number (N) of up to 30 was obtained in harmonic mixing using the LO wave as the microwave. The output depended strongly on the power of the LO wave and the Shapiro step spacing induced by the LO wave. It was approximately proportional to N−2.
Improving the reliability of space‐use traveling wave tubes and confirming the improvement
Authors: Mita Nagahisa
Published: July 2007

This study establishes the design method for the high reliability for the space‐use traveling wave tube (TWT) and presents the verification experiment of the high‐reliability performance for the case of TWT to be installed on CS‐3, as an example. Based on the relation between the cathode current density and the lifetime, which is derived from the degradation theory of the coated impregnated cathode, the convergence ratio of the electron gun and the cathode current density are optimized.

A method is presented which realizes the long‐life and highly reliable TWT, by the high‐reliability design and the screening based on theory. To verify the high‐reliability design, the wear‐out failure distribution is estimated by the accelerated temperature test; and the failure rate due to the random failure is estimated from the actual in‐orbit data. As a result of analysis of this mixed Weibull distribution, it is shown that the failure rate of 1000 fit, which is set as the design goal, can be achieved for 7 years of planned working period. It is shown also that by employing the high‐reliability design, the failure rate of 1000 fit or less can be achieved even if the working period of 10 years is defined.
A method of making an equivalent circuit for breaking arc
Authors: Kubono Takayoshi , Suzuki Hiroyuki
Published: July 2007

This paper considers breaking of the dc circuit by electrical contact and describes a method for measuring the voltage and current waveforms of the breaking arc and surge, as well as a method for deriving the arc equivalent circuit in the latter period of the breaking arc. The small inductance of the whole simulating circuit as well as the equivalent capacitance of the electrical contacts are determined so that the observed voltage waveform induced in the text circuit during the surge (i.e., the induced voltage waveform after chopping) and the voltage value in the resistor calculated in the simulating circuit agree.

Next, the equivalent arc resistance, coherence, and the phase angle are calculated from the voltage and current waveforms of the breaking arc, which contain the high‐frequency components. Using the equivalent capacitance, equivalent arc resistance and phase angle, the arc equivalent circuit is estimated that can simulate the measured arc voltage and current waveforms. It is seen as a result that the arc equivalent circuit in the latter discharge period of the breaking arc can be represented as a series‐parallel circuit where resistor ra1 is connected to the parallel circuit (ra2/Ca) of resistor ra2 and the equivalent capacitance Ca. When, for example, the Ag electrical contact on a relay breaks the circuit of dc 36‐V and a noninductive resistor 3 ω, the arc equivalent circuit in the 105 ∼ 106 band in the latter period of the breaking arc is constructed by ra1 = 65 ω, ra2 = −68 ω, and Ca = 200 pF.
Numerical consideration and some improvement of corner diffraction formulas applicable to spherical wave incidence
Authors: Higa Yoshifumi , Uchikawa Kiyoshi , Inagaki Naoki , Kikuma Nobuyoshi
Published: July 2007

Diffraction by a corner is one of the canonical problems remaining unsolved. However, several practical formulas have been proposed; any one of which must be able to be incorporated in the geometrical theory of diffraction (GTD). Of these, the corner diffraction formulas that can be applied to the spherical wave incidence are Burnside‐Pathak's formula (BP formula) and Zhang's formula (Z formula). In this paper, the BP formula and the Z formula are numerically compared by means of a hypothetical model consisting of a quarter infinite plane and an infinitesimal dipole. It is found that the BP formula and the Z formula become similar as long as they are not applied near the shadow boundary. The BP formula requires the edge parameters in the numerical process despite dealing with the corner diffraction. On the other hand, the Z formula needs only the parameters related to the corner. However, this formula experiences small discontinuity when the shadow boundary is traversed. In this paper, an empirical modification function is introduced into the Z formula so that a new corner diffraction formula (MZ formula) is proposed so that the diffracted field is uniform and continuous across the boundaries.
Fabrication of ferroelectric‐domain‐inverted gratings for LiNbO3 second harmonic generation devices by voltage application
Authors: Kintaka Kenji , Fujimura Masatoshi , Suhara Toshiaki , Nishihara Hiroshi
Published: July 2007

To realize a compact short‐wavelength coherent light source, development of an LiNbO3 waveguide quasi‐phase matched second harmonic generation devices is expected. To realize these devices, fabrication of the domain‐inverted grating is important. The authors discuss the fabrication of a grating with a period of about 3 μm near the surface of the z‐cut LiNbO3 crystal (with a thickness of 0.5 mm) by applying voltage. As the periodic electrode structure, the ladder electrode and the corrugation electrode were investigated. The distribution of the z component of the electric field induced under the periodic electrode was computed theoretically so that the structure of the periodic electrode effective for the grating fabrication was determined.

From the experimental investigation, it was found that the domain inversion was more likely to occur on the +z side and the application of the current limited pulse voltage (∼ 10 kV, width of 1 ∼ 40 ms) was effective and that a domain‐inverted grating could be fabricated almost uniformly under the entire electrode if the current‐limiting value and the pulsewidth were adequate. When a ladder electrode (electrode linewidth/period ∼ 0.2) is used in vacuum and when a corrugation electrode was used in insulation oil, suitable structures can be fabricated for the device, which is uniform in the waveguide cross section and the inverted width to the uninverted width was close to one to one under the periodic electrode.