bluuebunny/crossref_metadata_2025 huggingface dataset:
A K/C/S bands satellite antenna with frequency selective surface
Authors: Ando Makoto , Ueno Kenji , Kumazawa Hiroyuki , Kagoshima Kenichi
Published: July 2007

AK(30/20 CHz)/C(6/4 GHz)/S(2.6/2.5 GHz) bands offset satellite antenna with anS/Cbands feed horn and a low pass frequency selective surface (FSS) covering only part of a whole aperture angle, is designed, reproduced, its characteristic as an onboard antenna is confirmed and a design method and characteristic evaluation method for this type of antenna are established. In this antenna, three different frequency bands with different optimum aperture diameters share one reflector. the optimum aperture diameters peculiar for respective frequency bands (1.8 m forS, 1 m forC,Kbands) are realized equivalently by choosing the diameter of theS/Cbands feed horn and the size of FSS. the decrease in service area edge gain due to frequency bands sharing is about 1 dB, a satisfactory result compared to the case in which respective frequency band antennas are on board. the efficient analysis method assuming equivalent currents on the plane containing the FSS is derived to evaluate scattering from the small FSS. This method permits an antenna design with FSS size as a parameter; this was not considered before. the design and analysis of the antenna are confirmed by measurements.
Design and operation of a high‐speed bubble memory board
Authors: Toyooka Takashi , Sugie Mamoru , Aoki Hirokazu , Imura Ryo , Sugita Yutaka , Yoshizawa Shigeru , Ishida Kazuhiro
Published: July 2007

A magnetic memory board was designed and an experimental model was constructed for evaluation of its characteristics. the memory board contains eight 256 kb memory chips with an 8 μm cycle and operates with a rotating magnetic frequency of 312.5 kHz. These chips are driven by an already‐developed single‐chip memory module and a high‐speed rotating magnetic field drive circuit. to improve the peripheral circuits with respect to speed, reliability and size, several circuits were developed, including the transformer‐coupled pulse‐current generator for the functional part of the chip, the sense circuit with a high‐sensitivity comparator, and the high‐speed defect loop skip circuit using ROM and a shift resistor. the eight memory modules and their peripheral circuits were implemented on a 24.5 × 48.5 cm memory board. the circuits were adjusted and an examination was made of the defect loop detection and the operational margin, which indicated that stable operation was possible. Evaluation of the experimental memory board over a temperature range of 10° to 45° showed that the bias margin is larger than ±5 Oe, the rotating magnetic field amplitude margin is larger than ±6 Ue, and the pulse current phase margin is greater than ±150 as. the memory board was applied to the 64 Mb file in the database machine.
Self‐excited oscillation and monostable operation of a bistable light emitting diode (BILED)
Authors: Okumura Kenichiro , Ogawa Yoh , Ito Hiromasa , Inaba Humio
Published: July 2007

A new simple opto‐electronic bistable device has been obtained by combining a light emitting diode (LED) and a photodetector (PD) with electronic feedback using a broad bandpass filter. This has interesting dynamic characteristics which are expected to have such various applications as optical oscillators, optical pulse generators and optical pulsewidth modulators. the dynamic characteristics are represented by secondorder nonlinear differential equations. In the analyses of these nonlinear systems, instead of numerical analyses with a computer, an approximate analytical method devised for this purpose has been used. This method has been used for investigating the characteristics of the proposed device quantitatively. These include the frequency of oscillations, pulsewidths and hysteresis. the results of the analyses agree approximately with experimentally observed values, thus the dynamic characteristics of the proposed device can be explained.
Waveguide applicator with convergent lens for localized microwave hyperthermia
Authors: Nikawa Yoshio , Iwamoto Masanobu , Mori Shinsaku , Kikuchi Makoto
Published: July 2007

In the treatment of cancer by hyperthermia, it is desirable that the heating of the biological object be performed locally as noninvasively. For such a purpose, dielectric heating by electromagnetic wave presently is considered. the study of the design of the antenna (applicator) for local heating of a deep portion of the body is still in its infancy. This paper investigates a deeper penetration of the electromagnetic wave into the body, and proposes a convergent lens‐type waveguide applicator, where a metallic lens filled with dielectric material is attached to the waveguide. A heating experiment was performed using the proposed applicator at 2450 MHz for the phantom models consisting of a muscle singlelayer and muscle‐fat two‐layers, with electrical and thermal constants equivalent to those of biological tissues. Then the temperature distribution inside the model was examined in two dimensions using liquid‐crystal film. As a result, it is seen that by using the convergent waveguide applicator, the electromagnetic wave penetrates into the body by 40% more than in the case of traditional simple waveguide applicator, resulting in deeper heating. Furthermore, using the surface cooling device proposed for the applicator, it is verified that the local heating required in the hyperthermia can be realized.
Parasitic effects and polarization diversity of archimedean spiral antenna
Authors: Nakamo Hisamatsu , Yamauchi Junji , Sugiyama Yutaka
Published: July 2007

For the purpose of controlling the polarization of an Archimedean spiral antenna (SA), a parasitic spiral element is added on the same plane of a two‐wire SA. the radiation characteristics have been studied numerically and experimentally. First, the current distributions on both the active and parasitic elements are calculated from Hallen‐type integral equations in the frequency range of 3 to 6 GHz. Comparing the current distributions with those of a two‐wire SA and a four‐wire four‐terminal fed SA, we study the mechanism of polarization control. It is found that the present antenna operates as a linearly polarized element at lower frequencies and a circular polarization element at higher frequencies. It is found also that the input impedance does not change appreciably in frequency and hence the broadband nature of the conventional two‐wire SA is retained. Finally, it is confirmed numerically that circular polarizations in the opposite sense can be obtained over a wide range of angle due to change in excitation phase when four arms are excited.
Energy trapping of backward‐wave width‐extensional vibrations in piezoelectric strips and its application to filters
Authors: Watanabe Hiroshi , Shimizu Hiroshi
Published: July 2007

For the purpose of extending the useful range of trapped‐energy resonators and filters up to the middle band less than a few MHz, the energy trapping of the width‐extensional vibrations in a thin piezoelectric strip is studied. Since the width‐extensional vibration exhibits a dispersion characteristic of the high‐cut type in most piezoelectric materials, the backward‐wave energy trapping needs to be applied. As realistic methods, two approaches are discussed. In one of them, the areas on both sides of the excitation part at the center of the strip are short‐circuited by the electrode. In the other method, this portion is made unpolarized. In each approach, the energy trapping of the width‐extensional vibration is realized if the electrode in the excitation part is made a partial electrode with its width narrower than the strip width. A clean resonant response with few unwanted modes is obtained. A method for fabrication and experimental results are reported for a ladder filter and a single‐mode three‐terminal filter. Effectiveness of this device for a filter in the middle band is indicated.
I2L device circuit model with layout patterns
Authors: Shinmi Toshio , Inohira Susumu , Nagata Minoru , Hosono Etsuo , Iida Kyoichi , Furihata Makoto
Published: July 2007

An algorithm for CAD simulation model is discussed for an I2L circuit important for a bipolar analog‐digital hybrid LSI. A versatile modeling method is proposed here in which variation of the planar pattern of the I2L circuit is included. In this method the I2L device is divided into the injector, base electrode, collector and base termination. Each section is modeled by lumped elements consisting of transistors, diodes and resistors. the model parameters are expressed in terms of the main current density and main carrier concentration density of the I2L device. From this model, the terminal current and the carrier transit time can be related to the device shape. the terminal voltage dependence of the terminal current and the terminal current dependence of the gain bandwidth product as simulated by this method agreed within 10% with the measured values in the practical range (injector current 1 ‐ 100 μA). As an example of the application of this method to the I2L circuit, the injector current level dependence of the delay time of the 5‐stage ring oscillator and the usable current range vs. the input frequency of the 10‐stage counter are calculated and the simulation values agreed with the measured data within 10%.
Piezoelectric ceramic resonators using edge‐mode vibration
Authors: Iseki Yuji , Watanabe Hiroshi , Shimizu Hiroshi
Published: July 2007

To obtain miniaturized resonators with ease of support in the medium frequency range below several megahertz, piezoelectric ceramic resonators using the edge‐mode (the mode of vibration whose energy is confined to an edge of a thin strip) have been investigated. the theoretical analysis of the edge‐mode in a thin semiinfinite strip whose resonant frequency depends on its width has been carried out, and the characteristics of the edge‐mode, i.e., the resonant frequency, the distribution of displacement, and the distribution of planar dilatation, have become clear. In order to excite the edgemode vibration efficiently, three types of electrodes have been proposed which have envelopes matched with the distribution of planar dilatation. the optimum dimensions of the electrodes have been determined from the calculated results for capacitance ratios. Some piezoelectric edge‐mode resonators have been fabricated using Pb (Zr, Ti)O3 ceramics. It has been confirmed that resonators of this type have a small capacitance ratio between 20 and 40 approximately, frequency responses free from unwanted modes over a wide frequency range, and ease in mechanical support.
A study on SAW voltage‐controlled‐oscillator using a method of vector summation
Authors: Saito Shigeki , Urabe Shuuji
Published: July 2007

To achieve ultraminiaturization of synthesizers used in mobile radio this paper proposes the use of a SAW‐VCO incorporating a vector summation technique and describes studies regarding the important parameters of frequency purity and wide‐range variability. the SAW‐VCO using the vector summation method would be composed of SAW elements and a variable gain circuit and it can be expected that they would be ultraminiaturized (using monolithic IC technology). This paper focuses on the issues of high purity and wide‐range frequency variability considering the effect that the SAW delay line has on oscillation characteristics and examines, both experimentally and theoretically, the effects that amplitude ripple has on noise characteristics. In experiments in the 800‐MHz band, a frequency variation range of about 0.5% and C/N of 67 ∼ 75 dB were obtained (C is the carrier power and N is the noise in an 8‐ kHz band with 12.5‐kHz detuning).
Application of least‐squares method to adaptive channel equalizer with frequency sampling filter
Authors: Fujii Tetsoru , Harashima Hiroshi , Miyakawa Hiroshi
Published: July 2007

This paper presents a new design method for a frequency sampling adaptive equalizer using the least‐squares method and reports the results obtained in analyzing the equalizer performance. This system employs an adaptive equalizer configuration in which a cyclic code equal to the tap length is used as a test signal with the receive signal and the reference signal each undergoing a discrete Fourier transformation using a frequency sampling filter and applying the least‐squares method in a one‐to‐one relationship to each DFT coefficient. A condition for the implementation of this system is that the test signal be a cyclic code, but this system requires fewer arithmetic operations than any other system employing the least‐squares method. the system presented here employs a high‐speed convergence algorithm in the initial training period and after convergence is accomplished it switches to a gradient method using a frequency sampling adaptive equalizer. In simulation tests with telephone lines it was found that this equalizer converged in about one‐third the time required for the transversal adaptive equalizer.
Time spread transmission system using block conversion
Authors: Ohtake Kohhei , Ohue Kenji
Published: July 2007

In the digital transmission of non‐telephone signals, impulse noise interference, such as switching machine noise, interruptions, etc., become problematic and it has become necessary to suppress them. to suppress impulse noise interference efficiently, this paper presents a time spread transmission system, which transmits digital signals spread on the time axis through a block conversion, and discusses the system construction and the noise attenuation characteristic. First, the requirements for the time spread matrix in a general communication channel with impulse noises and random noises, such as thermal noise, crosstalk, etc., are described. It is clarified that for the matrix a cyclic orthogonal one is most suitable. For a single impulse noise interference, noise amplitude attenuation characteristics of the system are improved by 3 dB, compared with those of the conventional smearing‐desmearing filter method. Finally, the bit error rate is estimated for burst noise interference channel on a statistical noise model and it is shown that the bit error rate reduction of two decimals is achieved for the case of transmission rate 64 Kb/s and spread time 8 ms.
Centralized data collection systems via meteor burst
Authors: Mukumoto Kaiji , Nagashima Noriaki , Fukuda Akira
Published: July 2007

Ionized trails caused by the entry of meteors into the atmosphere provide probabilistic communication paths between two points over the horizon. Three protocols for a data collection system via meteor burst communication channels are studied and evaluated. the first is merely the pure ALOHA protocol applied to the probabilistic channel. the second is called the IT protocol. It has a frequency division idle‐tone channel. A terminal which has a message observes this channel and determines whether the main channel is open or closed for it. the third protocol, the so‐called ITT protocol, also has idle‐tone channel. Messages are divided into many blocks (this message structure is called “Tokage (lizard)” type) and go‐back‐N ARQ protocol is utilized. We show that the idle‐tone and the lizard‐type message with ARQ, are extremely effective to increase the channel utilization in such systems. It is also shown that high channel utilization can be achieved by the use of the ITT scheme even in a probabilistically generated and terminated communication channel such as meteor burst communication path.
Axis misalignment and splice loss estimation of single‐mode optical fiber splicing using core direct monitoring
Authors: Kawata Osamu , Hoshino Koichi , Miyajima Yoshiaki , Ohnishi Masatoshi , Ishihara Koushi
Published: July 2007

This paper examines the splicing loss due to axis misalignment in the splicing of single‐mode optical fibers using direct core monitoring and discusses the methods for reducing such loss and the techniques for estimating it. Axis misalignment is strongly dependent on the offset between the monitoring location and the actual position due to the fiber lens effect and core eccentricity as well as on the precision of the core monitoring system. Taking into consideration the indeterminateness of the relative position of the fibers, we analyze this relationship by means of a statistical technique and, using a direct core monitoring system with transmitted light, verify the appropriateness of the theory by means of experimental studies. Further, it is shown that it is necessary to reduce the alignment error due to core eccentricity and that it is possible to align the cores to a precision of better than 0.5 μm by correcting the core center position from the observed eccentricity. In addition, by considering the surface tension effects during fusion we can explain the relationship to axis shift before and after splicing and, if the axis alignment precision is given prior to splicing, we can estimate the splicing loss distribution. We also show that it is theoretically possible to achieve an average splicing loss of less than 0.1 dB with single‐mode fibers using this direct core monitoring method when the axes are aligned to within 0.5 μm.
Quasi‐optical diplexer by rectangular metallic mesh
Authors: Sato Ikuro , Tamagawa Susumu , Iwata Ryuichi
Published: July 2007

This paper provides the results of theoretical and experimental studies to realize a broadband quasi‐optical diplexer with polarization‐independent characteristics, using multilayer rectangular metal meshes. A rectangular metal mesh is usually used in the inductive region below the mesh resonant frequency. In the theoretical analysis based on the mode matching method, it is concluded that the anomalous resonance of the mesh appearing below mesh resonant frequency in TM oblique incidence is caused by the higher‐order modes generated on the metal mesh surface. This phenomenon can not be explained by the equivalent circuit analysis, in which metal mesh is decomposed to two orthogonal metal strip gratings. A bricktype rectangular metal mesh is proposed in which the anomalous resonance can be eliminated from the operating frequency region. It is shown theoretically and experimentally that one can realize a new metal mesh of which the transmission characteristics below the mesh resonance do not vary in accordance with the incident polarization mode. A design method of quasi‐optical diplexer using this brick‐type metal mesh is described and the experimental results of the filter designed for diplexing the six, 4 GHz and fourteen, 11 GHz signals are reported. It is confirmed that broadband diplexing is possible with a stacked rectangular metal mesh and that the design method is legitimate.
High‐precision automatic ellipsometer and whereby evaluation of a very thin silicon‐oxide layer
Authors: Iwamura Soichi , Nishida Yasuaki
Published: July 2007

To measure automatically both the thickness and the refraction of films of several tens of angstroms, e.g., a barrier oxide for MNOS memory with high precision, a high‐speed automatic ellipsometer has been developed which can measure accurately the extinction positions of polarizer and analyzer. Hence, the polarizer/analyzer extinction positioning accuracy of 1 × 10−4 degrees has been obtained in the repeatability test during the same sample measurements. By aligning and calibrating many optical components, a perfect extinction has been obtained in crossed Nicols with a quarterwave plate (PCA). For the position detection, the optical encoder scales drawn by electron beam exposure system are read by a laser beam detector, resulting in positioning accuracy of 10−4 degrees. Next, an example is shown where the thickness of a native oxide formed on a silicon wafer is measured by this system. the possibility is shown of evaluating the oxide surface roughness with the standard deviation around the average thickness from the polarizer/analyzer extinction curve, the measured extinction factor, and the deduced value from the oxide model.
Three‐level optimization algorithm for nonconvex problems with block angular structures
Authors: Sakawa Masatoshi , Member Regular
Published: July 2007

A three‐level optimization algorithm is proposed for a large‐scale nonlinear programming problem with nonconvexity and block angular structures based upon the general duality theorem. In the three‐level optimization algorithm the augmented Lagrangian function as well as the auxiliary variables of the second term in the augmented Lagrangian function are introduced to resolve the so‐called duality gap and conversion is done to obtain an additively separable form. Then, an independent partial problem is solved and the dual function is determined by using the sum of the object functions in the partial problem. Further, an example of application with simple numerical data and nonconvexity is shown to confirm appropriateness of the proposed three‐level optimization algorithm.
Simulation of a noise source with a 1/f spectrum by means of an RC circuit
Authors: Motoishi Kohji , Koga Tosiro
Published: July 2007

The fact that a power spectrum is inversely proportional to frequency is of interest in the fields of engineering, physics, and physiology. This paper presents a theoretical design method for a network whose power spectrum response to noise is a good approximation to the so‐called 1/f‐response in a given frequency band between lower and upper limiting frequencies. The network is a filter whose transfer function to white noise is 1/√s. The input impedance of a cascade connection of semi‐elementary sections composed of symmetrical RC lattices whose image impedances are 1/√s is a close approximation to 1/√s. Design formulas and diagrams of the approximating function, showing the relationships between the parameters of the frequency band, the approximation and the degree of the approximating function are given. A filter whose transfer function is an approximating function is realized by a cascade of symmetrical RC lattices and an operational amplifier. An experimental test of a tenth degree filter shows good characteristics in the frequency band 1 Hz ‐ 100 kHz. It is shown that the approximating function is applicable in the design of a Wiener filter for the reduction of 1/f fluctuations.
Speech synthesis using generalized cepstrum
Authors: Kobayashi Takao , Imai Satoshi
Published: July 2007

As a speech analysis method using the generalized cepstrum there is a method based on a generalized logarithmic function instead of a logarithmic function as an evaluation scale. This paper presents a speech synthesis system using the generalized cepstrum, which is defined as the Fourier coefficients of the generalized logarithmic spectrum. The direct approximated digital filter using the Padé approximation, which is the inverse function of the generalized logarithmic function, is used as a synthesis filter. Since this filter not only gives a good approximation of the desired generalized logarithmic spectrum by a generalized cepstrum but also since the values of generalized cepstra correspond to the filter coefficients as they are, it is easy to determine the synthesis filter coefficients. Since the synthesis system in this paper is fully compatible with the one based on the conventional cepstrum method, it is possible to synthesize speech by the generalized cepstrum without changing the speech synthesis system based on the conventional cepstrum method. Also, using this synthesis system, it is possible to synthesize speech by the conventional cepstrum method as a special case of this method. With proper choice of the parameters of the generalized logarithmic function, the synthesized speech by this method is of higher quality than that by the conventional cepstrum method.
An analysis of pulse response with phase delay in transistor circuits by means of state variable approach
Authors: Ishibashi Shinichiro , Member Regular
Published: July 2007

The fact that the pulse response of a transistor circuit is accompanied by a phase delay is well known. The quantity β(s), which plays the role of the frequency response of α(s), is expressed in terms of polynomials and the transformation formulas are obtained by introducing a state variable into β(s). After α(s) is set equal to d0e−sm/ωa, this transformation gives a response that agrees satisfactorily with measurement. This is true even when the measured pulse response has a phase delay from the start of response to the steady state conditions. This paper also gives the phase delay element value. When the delay time contained in the element is compared to m/ωα obtained from the response, the delay time of the pulse response can be directly determined within the phase interval from 45° to 90°. In addition, the relationship between the location of centroid of the impulse response coordinate axis and the 50% rise time of the indicial response and the carrier transit time is also investigated.
A new reliability evaluation method based on using the parasitic MOS formation phenomenon
Authors: Kumura Masao , Fujita Kazuya , Hayakawa Masao , Aoki Yoshimasa
Published: July 2007

One of the instabilities in plastic‐encapsulated MOS LSI is due to leakage caused by parasitic MOS formation. This paper uses this parasitic MOS leakage phenomenon to evaluate the surface reliability of new MOS. In this investigation the center of the gate electrode is omitted, and an MOS transistor with a partial gate structure is fabricated; plastic encapsulations are used, and the source‐drain leakage current variation with time is investigated with a voltage applied between source and drain. The results are shown to be different with different plastic encapsulation. The maximum leakage current increase rate is denoted by α. The parameter α is temperature‐dependent and a linear relationship exists between the logarithm of α and the reciprocal of the absolute temperature T. The activation energy is found to be 1.1∼1.4 eV. The theoretical formula of the physical meaning of α shows that α is proportional to the diffusion constant of the parasitic MOS formation, and the correctness of the new evaluation method using α is confirmed. Our method has good repeatability. In addition, it permits an easier and, because of high sensitivity, a faster evaluation than the conventional method using variations of the threshold voltage VT.
An optical guided‐wave dye laser and directional coupling amplifier
Authors: Hamano Osamu , Sasaki Keisuke
Published: July 2007

The properties of a new type active thin‐film optical waveguide with layers of Corning glass 7059, Pyrex, and Rh 6 G dye formed on a fused quartz substrate are discussed. It generates superradiant emission when excited by a pulsed N2UV laser. When the top layer is shaped as a square, resonant behavior is observed between the corner reflectors formed by the edges on the diagonal. When the optical path is displaced normal to the diagonal, a distinct resonance is observed. This structure was used as a directional coupler and the coupling efficiency was found to depend on the waveguide length. These properties can be treated theoretically relatively simply in terms of a complex propagation constant with a positive imaginary part.
Performance analysis of some ARQ protocols
Authors: Iisaku Syun‐Ichi , Hatori Kozo
Published: July 2007

ARQ (Automatic Repeat Request) schemes are methods for controlling the error in data transmission. Among the schemes previously proposed are the selective repeat, the GO‐BACK‐N, and the combinations as well as the modifications of these schemes. The analysis of these schemes has been performed on the basis of a simplified model. This paper presents the analysis of several ARQ schemes using a more complex model which takes into account the long propagation delay (such as satellite links), transmission delay associated with retransmission, the system internal time, and the buffer size of the sending station. A concept of equivalent channel holding time is used in conjunction with a M/G/1 queueing model for the analysis of the system throughput as well as other characteristics.
Optical time domain reflectometer for backscattered light
Authors: Nakahira Mizuho , Tokuda Masamitsu , Omote Koji , Kosugi Takayuki , Kitagawa Kazumaro
Published: July 2007

It is possible to detect the point of breakdown and to obtain the loss of optical fibers by measuring the backscattered light caused by Rayleigh scattering. This paper describes design and test results for a small, light‐weight, high‐performance optical time‐domain reflectometer. To obtain masking functions for excessive pulses such as those obtained by Fresnel reflection, we use an image dissector as the detector and obtain a 50‐dB masking attenuation. A digital averager is used to improve the S/N ratio. The time required for 1000 averagings is only 40 seconds. To prevent drift, an AC coupled amplifier and a zero‐level sampling system are used and sufficient temperature stability is realized. The experimental reflectometer is able to detect the breakdown point as far away as 8 km with backscattered light and at 14 km with perfect end Fresnel reflection. The error in the loss measurement is less than 0.05 dB for the distances up to 4 km. From these results, the tested reflectometer is found usable in practice.
Evaluation of large scale T‐S‐T types of networks controlled by homing‐type path hunting strategies
Authors: Ogino Nagao , Saito Tadao , Inose Hiroshi
Published: July 2007

One of the important problems in the design of switching systems is to arrive at a switching network with high efficiency. In order to obtain a switching network satisfying economical requirement for the total switching system including the processing devices, the system must be evaluated from the viewpoint of the amount of processing in path‐hunting, as well as traffic efficiency and hardware cost. From such a viewpoint, the authors conducted evaluations based largely on simulation of the path‐hunting processing in the switching network. However, since simulation involves practical difficulties in the evaluation of a large‐scale switching network, a simple and theoretical method is desired to evaluate the amount of processing in path‐hunting. This paper presents a theoretical method of evaluation for the homing‐type path‐hunting system, which is superior from the viewpoint of blocking probability and the amount of processing. The effectiveness of the proposed method is demonstrated. Using the proposed method, the relation between the path‐hunting scheme and the blocking probability is derived and actual large‐scale T‐S‐T switching networks are evaluated from the viewpoint of the amount of processing in path‐hunting. The result of evaluation indicates that a switching network with higher traffic efficiency tends to require a larger amount of processing in a large‐scale switching network as well. The optimum switching network type is indicated, considering the amount of processing in path‐hunting.
Some comments on the analysis of electromagnetic fields in inhomogeneous media
Authors: Yamaguchi Shoji , Hosono Toshio
Published: July 2007

Among the principal approaches to electromagnetic field analysis in an homogeneous medium are numerical methods. The homogeneous multilayer approximation used in numerical methods is invalid when there is wave equation singularity. This paper demonstrates that the finite difference method is equivalent to the homogeneous multilayer approximation methods when the number of subdivision is increased; further, it is shown that finite difference methods also can be invalid. To analyze electromagnetic fields in the medium for which the wave equation contains a singularity, we propose here an inhomogeneous multilayer approximation method (a piecewise linear approximation) based on the power series solutions. A technique is presented for improving the homogeneous multilayer approximation method and the finite difference method by using the results of piecewise linear approximations. We further propose a modified multilayer approximation method by combining advantages of various methods. The principal features of the modified multilayer approximation method are as follows: 1) Calculations are possible even when the wave equation has several singularities; 2) the method is applicable to the structure with arbitrary medium profile; 3) the solution near the singularities can be obtained relatively easily; 4) a desired degree of accuracy can be obtained by increasing the number of subsections; and 5) no extensive mathematical background is required.

The modified multilayer approximation method is used to analyze the reflection of a plane wave from an inhomogeneous plasma slab. Presented in graphical manner are the power reflection coefficient, the energy absorption, the electromagnetic field distribution inside the slab and the power flow.
Grating diplexer using dielectric waveguides for millimeter wavelengths
Authors: Shinonaga Hideyuki , Kurazono Sadao
Published: July 2007

A new grating diplexer using dielectric waveguides is proposed for millimeter‐wave applications. It consists of two symmetric rectangular dielectric waveguides in which two 3‐dB hybrids and two gratings for band‐stop filters are contained. Hence, it is convenient for integration. In the analysis of grating structures, we introduce equivalent circuits to which F, S, and T matrices are applied to obtain the dispersion properties and the frequency characteristics of reflection and transmission. Experimental data obtained at millimeter‐wave frequencies agree well with theoretical values. It is found that millimeter‐wave grating diplexers can be used as bandsplitting diplexers and channel diplexers in millimeter‐wave communication equipment.
Network control system using traffic database in public telephone network
Authors: Mase Kenichi , Kajiwara Masaichi , Yamamoto Hisao , Shinohara Masaaki
Published: July 2007

A traffic ontrol system using geographically distributed traffic databases is proposed. Each data base maintains nationwide network information such as the busy/idle statuses of customer lines and trunk groups.

A local switching system accesses the regional database to process each outgoing call adequately. Each database periodically obtains local network information from all switching systems within the region of its coverage, transferring it to other data bases. Used in this system are, for example, satellite broadcast channels which update simultaneously the information stored in the data bases.

For this traffic control system, (1) an acceptable time delay required to update the databases and to set up calls is obtained; (2) the effectiveness of this control system for dealing with focused overload is evaluated; and (3) loads on signaling channels, the satellite channel and the database system also are evaluated.
Characteristics of signal error and signal‐to‐noise ratio in γ‐Fe2O3 thin film disks
Authors: Ishii Yoshikazu , Terada Akira , Ishii Osamu , Ohta Satoshi , Nakagawa Takehiko
Published: July 2007

Signal errors and signal‐to‐noise ratios of reaction‐sputtered γ‐Fe2O3 high‐speed magnetic disks (diameter 210 mm) have been investigated with a memory density of 620–640 bit/mm and a core width of 15 ‐ 16 um. The results are summarized: (1) Errors have been reduced by removing substrate surface and exfoliation defects of the sputtered magnetic film. (2) Errors on a single surface are reduced to less than 10 with a high purity substrate having a small number of impurity segregations. (3) Exfoliation errors have been completely removed by adopting triple sputtering. (4) Investigation of the results obtained with various sputtering processes and sputtering conditions shows that the signal‐to‐noise ratio is closely related to the crystal grain size of the γ‐Fe2O3 magnetic film. (5) Addition of Cu is found to be effective in suppressing crystal grain growth, and can improve the signal‐to‐noise ratio.
High‐rate, low‐temperature sputtering method of facing‐targets type and its application for deposition of magnetic films
Authors: Hoshi Youichi , Naoe Masahiko , Yamanaka Shun'Ichi
Published: July 2007

To realize high‐rate, low‐temperature sputtering, two parallel targets were used and a magnetic field was applied perpendicular to them. The γ‐electrons emitted by the targets contribute to formulation of a high‐density plasma between the targets and to controlling the γ‐electrons striking the substrates. As a result, the authors were successful in depositing such magnetic materials as iron and nickel on a substrate without heating at 50 times the rate in ordinary diode sputtering. This method also prevents high‐energy ions from hitting the substrate and permits deposition of a film of large area with uniform thickness. The observed profile of the film thickness agreed with the calculated one in which the cosine law of sputtering was assumed. A practical model of the present sputtering apparatus was fabricated with permanent magnets and its performance was investigated.
An algorithm for generating circuit diagrams of LSIs
Authors: Nishiguchi Nobuyuki , Kawanishi Hiroshi , Nakao Masumi , Kishimoto Aritoyo
Published: July 2007

The degree of IC integration has shown yearly increases. Hence, the amount of layout data also has increased. Therefore it is very important to verify that a given circuit is realized correctly on a layout. To simplify verification we reconstruct the diagram of a given circuit from its layout data. We present an algorithm for reconstruction and describe a system which incorporates it. The circuit diagrams reconstructed by this algorithm resemble these drawn by layout designers. Hence it is a very effective means of layout verification. In this algorithm we use a graph to show the interconnections of transistors given by layout data. We group transistors into a number of subgroups so that each group forms a logical unit. Then we determine the positions of the transistors within each group and the positions of the logical units. Finally we reconstruct a circuit diagram resembling the hand drawn one by determining the final positions of the transistors of the circuit based on those positions.
Dipole array applicator for hyperthermia
Authors: Terada Noriyoshi , Amemiya Yoshifumi
Published: July 2007

Hyperthermia (heating therapy) has attracted attention as a possible cancer therapy. Hyperthermia treats an affected area with heat. It is effective alone and its effect is multiplied when combined with other treatments. Many heating devices already proposed limit their heating to the surface; therefore, proposals for devices which can perform deep heating are strongly demanded. This paper proposes an applicator for hyperthermia which provides deep heating by exciting in‐phase dipole elements arranged on a circumference. Theoretical study is conducted to determine numerically various parameters of the proposed applicator and its temperature rise during heating. It is shown that deep heating with less overheating on the surface is possible with this proposed applicator. Furthermore, temperature rise at the tumor area can be expected with heating using a relatively low frequency but overheating and multiple hot‐spots (heating point) as in the case of conventional high‐frequency heating are not produced.
A method for fast synchronization in spread spectrum multiple access communication systems
Authors: Sugiyama Hisayoshi , Amemiya Yoshifumi
Published: July 2007

A feature of the spread‐spectrum multiple‐access communication system is that multiple users can simultaneously utilize a common frequency spectrum, and applications to vehicle and satellite communications are anticipated. A problem, however, is that several seconds are required to establish synchronization for the PN code used on the receiving side. To solve this problem, it is proposed that the information for synchronization be acquired using a surface acoustic wave matched filter, but this is difficult in multiple‐access communication owing to the restriction on the number of taps. A new code applicable to the spread‐spectrum multiple‐access communication system with direct spread scheme aimed at the communication of analog information is proposed. It is shown that the surface acoustic wave matched filter, which has fewer taps and is more practical, can be used to drastically decrease the time required for the establishment of synchronization.
The semiconductor pressure transmitter using the diffused piezoresistive diaphragm sensor
Authors: Kozuma Taisaku
Published: July 2007

Because of their high output voltage and convenience of use, pressure sensors composed of strain gages diffused onto semiconductor wafer diaphragms are widely used in research. Here we consider the use of diffused semiconductor strain gages in industrial pressure or differential pressure transmitters for process control. These pressure sensors consist of diffused semiconductor strain gages produced by integrated circuit technology on an elastic silicon wafer diaphragm, and an amplifier. The 24 VDC input voltage and 4‐20 mA output signal may both be carried by the same two wires. This paper describes the investigation of industrial pressure sensor designs and presents experimental data on their characteristics. The specimens tested had a nonlinearity error of +0.02 ∼ +0.2%/25 kg/cm2, a zero point shift of −0.2 ∼ + 0.3%/5 kg/cm2/10 deg C, a temperature‐dependent span variation of +0.4 ∼ −0.8%/5 kg/cm2/10 deg C, and a hysteresis value of −0.05 ∼ + 0.1%/5 ‐ 25 kg/cm2. These results indicate that diaphragms with diffused strain gage sensors are suitable for use in industrial pressure transmitters.
Canonical realization and round‐off noise analysis for combinatorial filters
Authors: Kawarai Shigeyoshi
Published: July 2007

Recent developments in memory devices have led to the proposal of a direct method of constructing combinatorial logic filter which uses bit serial operation (i.e., memory and reversible adder are used for bitwise summing of the result of weighted addition). By combinatorial construction it is possible to increase operating speed, simplify the hardware and decrease the power consumption, leading to an efficient digital filter. This paper applies bit serial operation to the canonical construction, leading to a combinatorial filter with memory capacity of 1/2N‐1. Then, bit parallel‐serial operation, which sums up the result of multibit weighted addition, is applied to the canonical construction of the second‐order section, leading to a digital filter with t/I times higher speed than in the past. It is noted that the roundoff noise in the combinatorial filter is independent of the input data, and a noise evaluation model is proposed in which the error can be independently discussed. Using the proposed model, the mean‐square error of the filter output can easily be determined. This paper deals with the drawbacks in the past theory of noise evaluation for the direct construction and performs a noise analysis for the canonical construction. The result is useful in application to LSI design for a high‐speed digital filter.
Decoupling capacitor of substrate bias voltage on dynamic MOS RAM chip
Authors: Taniguchi Makoto , Yamada Michihiro , Kumanoya Masaki , Kobayashi Toshifumi , Nakano Takano
Published: July 2007

In a 64‐Kbit dynamic MOS RAM which has a single 5‐V substrate bias voltage generator, the substrate voltage varies largely with the charge‐discharge process of the bit line as well as of the decoder circuit. Depending on the circuit design, the rate of variation can reach 90%. An example of reducing the sensitivity of a sense amplifier which utilizes a separate memory is shown. Also, in order to reduce the variation of substrate voltage, formation of a decoupling capacitor having a double‐layer polysilicon structure becomes effective. The double layer is underneath the aluminum layer on the chip. Problems associated with this structure are that, due to the alternating current of substrate voltage in dynamic operation, electrons are injected into the substrate, depending on the inversion layer of the MOS capacitor. This results in reduction of memory cell voltage “H”. Moreover, in this paper, we propose a new method of determining the electron diffusion length using the above phenomenon. Also, in order to prevent electron injection from the inversion layer, a P+ layer is replaced. A desirable disturb refresh time for 64 K dynamic RAM is obtained. This RAM has a decoupling capacitance of 600 pF (27% of the total substrate capacitance). In addition to this, variation in the substrate voltage is decreased to about 30%.
Design of fir lowpass matched filter pairs with zero intersymbol interference and quasi equiripple stopband attenuation
Authors: Takebe Tsuyoshi , Higashide Hiroshi , Nishikawa Kiyoshi
Published: July 2007

A method is described for designing FIR lowpass filters for receivers and transmitters in data transmission systems. Choosing both filters as a matched pair, the objective is to provide each filter with quasi‐equiripple stopband attenuation and to make the overall impulse response satisfy zero intersymbol interference (zero ISI). The method consists of four steps. First, the ideal overall transfer characteristics are approximated in terms of a Fourier series, and the initial zeros of the characteristics are obtained. Second, one half of the mirror image zeros are used for finding zeros on a unit circle so that the single filter has equiripple stopband characteristics. Third, in the overall transfer function, these stopband zeros are fixed as double zeros. The overall impulse response is successively approximated by changing the mirror image zeros in the passband so that the zero ISI condition is satisfied. Finally, the obtained mirror image zeros are divided into two groups, one is allotted to the transmission filter and the other is to receiving filter so that they form a matched pair. In the zero ISI approximation in the third stage, a good initial response is obtained. Further, since the number of variables is equal to the number of zero ISI conditions, the approximation converges accurately and quickly. As a design example, a filter pair is shown in which both the transmission and receiving filters are 59th orders. The ISI is only 2.2 × 10‐4% compared to 0.4% found in a different design method.
Discriminator with partial response detection of nrz. fsk signals
Authors: Nakamura Yasuhisa , Members Yoichi Saito, Regular
Published: July 2007

In the TDMA subscriber loop radio communication system, large carrier frequency deviation exists in burst signals from subscribers to a base station. A modulation/demodulation technique, which is suitable for the burst transmission with large frequency variation, is studied in this paper. First, problems in the terrestrial TDMA system and clarified and it is shown that the use of conventional FSK‐discriminator detection causes large CNR degradation due to the variation. Next, differential FSK‐Partial Response Detection (DFSK), which can cope with the frequency variation and has a simple structure, is proposed and its principle and structure are described. Furthermore, the intersymbol interference and adjacent channel interference characteristics are evaluated theoretically and the bit error rate (BER) characteristics are evaluated experimentally. As a result, the optimum modulation index and IF‐band reception band path filter are obtained. Finally, the optimum transmission system of DFSK designed for wide‐band Digital Radio Subscriber Loop System using 26‐GHz band is described. DFSK is shown to be a practical and promising modulation/demodulation system for a terrestrial TDMA communication system, on which a large demand is expected in the future.