bluuebunny/crossref_metadata_2025 huggingface dataset:
Equivalent circuits of binomial‐form nonuniform transmission lines and their application
Authors: Kobayashi Kunikatsu , Nemoto Yoshiaki , Satos Risaburo
Published: July 2007

Among various nonuniform distributed‐parameter transmission lines, the exponential line and binomial line can be analyzed by obtaining the rigorous solutions of the telegraph equation. The exponential line in which the line parameters change exponentially has been studied in the past, but the binomial line has not yet been studied systematically because the rigorous solutions for the voltage and current distributions differ depending on the characteristic impedance. In this paper, the rigorous solution of the telegraph equation for 2nth‐order binomial lines is derived and its equivalent circuit is constructed by a cascade connection of uniform distributed‐parameter lines, lumped reactance elements and ideal transformers. Further, the binomial line is made equivalent to the exponential line by equating the characteristic impedances of both lines at the input and output terminals and by letting the order n of the binomial line be infinite. Finally, as an application example, the high‐pass filter consisting of the series lumped capacitance and uniform distributed‐parameter line is constructed by the quadratic binomial lines and series lumped capacitances.
A simulation‐type RC active filter using a negative impedance converter
Authors: Ishibashi Yukio
Published: July 2007

The LC simulation‐type active RC filter has a lower element sensitivity than the cascade active RC filter. This paper proposes a method of realizing the LC simulation type active RC filter which is suitable for the bandpass filter with finite number of poles. The resistor is converted to a parallel circuit of ‐L, ‐C and ‐R by the frequency‐dependent NIC composed of two resistances, two capacitances and one op‐amp. Then the LC filter is realized by converting all elements to negative elements. The sixth‐order simultaneous Chebyshev filter is constructed. The test result indicates the effectiveness of the present method. The present method requires smaller number of elements (particularly, active elements) than any other methods.
Analysis of loop antenna with circular reflector and its properties
Authors: Iwashige Jiro
Published: July 2007

The method of equivalent edge currents is applied to derive diffraction fields by an edge of a cone conductor. Geometrical‐optical fields (direct wave + reflected wave) are added to the diffraction fields and both fields are Fourier analyzed to find current distirbutions and input impedance. Radiation pattern and power gain are obtained in terms of diffraction coefficients derived by Kouyoumjian et al. Calculations are made mainly for a one‐wavelength loop antenna and the effects of the disk reflector diameter and wedge angle are clarified. The power gain is 1 dB larger than that of an infinite plane reflector. Theoretical results generally agree with observations.
A validation method of communication protocols free from data block loss and duplication
Authors: Yoshida Yutaka , Nomura Masayuki , Tanakas Yoshikazu
Published: July 2007

This paper presents a validation method of communication protocols. Many validation methods of communication protocols have been reported, mostly aiming at validating only the deadlock. The method will provide a means of discriminating the deadlock, data loss and duplication. First, the operation of two terminals which are communicating with each other according to a protocol with one block sending at one time (the most widely applied procedure) is defined as an automaton of two sets of terminals or terminal automaton. Second, the communication system is described as another automaton (communication automaton) composed of the former automations, with due regard to error characteristics of transmission paths caused by noise. Third, the state transition diagram of the communication automaton is utilized to provide the discrimination method. We will apply it to the JIS standard basic procedure and demonstrate its usefulness.
Magnetostatic wave delay lines using an inhomogeneously magnetized Yig Slab
Authors: Masaoka Yoshihiko , Tsutsumi Makoto , Ohira Takoshi , Kumagais Nobuaki
Published: July 2007

A new delay line for magnetostatic wave is proposed. The line consists of a ridge magnetic pole piece. Theoretical results are compared with observed ones for a (110)‐cut YIG slab. Dispersion of group delay is improved by a factor of 2 to 3 compared with an ordinary delay line using a planar pole piece, and the propagation loss is as small as 25 dB, that is, close to loss of bulk propagation in YIG.
Difference‐frequency generation in three‐dimensional linbo3 optical waveguide
Authors: Uesugi Naoshi
Published: July 2007

Since an optical waveguide can carry the light wave of high power density, very efficient nonlinear optical devices may be realized using the optical waveguide. Second harmonic generation in an optical waveguide has been reported. However, little has been known on difference‐frequency generation. This paper discusses generation of difference‐frequency signal in a three‐dimensional LiNbO3 optical waveguide which utilizes temperature variations of birefringence of LiNbO3 as a phase matching mechanism. From calculations of phase matching conditions, tuning characteristics and conversion efficiency of the difference‐frequency generation, it is found that the phase matching condition can be satisfied readily over a wide wavelength region and that the conversion efficiency in a 1‐cm long optical waveguide reaches a few percent with 100 mW pumping input. Further, using a three‐dimensional Ti‐diffused LiNbO3 waveguide, we generated difference‐frequency signals of a Rhodamine 6 G dye laser and a Nd:YAG laser. By changing the wavelength of the dye laser and the temperature of the optical waveguide, we generated difference‐frequency signals from 1.035 μm to 1.19 μm. At 1.035 μm wavelength, we generated 2.4 μW signals from the dye laser input of 70 mW and the Nd:YAG laser input of 1.7 mW.
Minimax design of model‐following control system
Authors: Yahagi Takashi
Published: July 2007

This paper presents a method for the design of linear regulators subject t o minimum performance. This regulator is designed such that it follows the reference model which exhibits desirable transient response. If the quadratic performance function is used for the transient response errors of the control system and the reference model, the optimum solution depends on the in it ial state of the control system. Such initial ‐ state dependency must be eliminated in the design of regulators. A minimax design for the model‐following control system i s described for cases with and without compensators with performance functions, the calculation for obtaining the optimum solution becomes complicated, i. e, it becomes impossible to obtain the minimax solution by directly solving the necessary condition of the optimum solution. This paper proposes a numerical algorithm by which the minimax solution can readily be attained.
Improvement of front‐to‐back ratio by choke loaded at edge of parabolic antenna
Authors: Kaneki Toshiyuki
Published: July 2007

When the parabolic antenna is loaded in its periphery with a choke, the electric current inside the reflector can be suppressed so as to improve the front‐to‐back ratio. This paper establishes the function of the choke and presents qualitatively its effect. A primary radiator used is a shot radiator and the practical antenna is represented by a two‐dimensional model to simplify the treatment in which the function of the choke can be represented by a single integral equation. After solving the integral equation, the choke function and its equivalent magnetic current are obtained, the pattern of the antenna loaded with choke can be calculated from the combined fields due to the magnetic current and the primary radiator, and the results are compared with the measurement. For example, for the case of an antenna 40 cm in diameter loaded by a 3 mm choke at 12 GHz, 5 dB improvement in front‐to‐back ratio can be achieved. Also shown is that the magnetic field component of the slot contributes about 1 dB to the effect.
A finite element model for the inverse problem in electrocardiography
Authors: Murai Tadakuni , Kagawa Yukio
Published: July 2007

A finite element model suitable for solving the inverse problem of electrocardiography is proposed. The body field is divided into two regions, the region without current source which is exterior to the heart and the cardiac region where the current sources are present. For the former region, the finite elements are so constructed that the discretized transfer matrix between the body surface nodes and the epicardial nodes can be uniquely determined. For the cardiac region, the treatment is basically the same as the former in the sense that the number of nodes assigned to the cardiac current sources within the heart is taken to be identical to that of the epicardial nodes. This arrangement provides a unique solution, though special devices for high‐order elements must be carefully arranged. Transfer characteristics that relate the surface potentials to the current sources are thus achieved.
Photo‐excited DLTS: Measurement of minority carrier traps
Authors: Takikawa Masahiko , Ikoma Toshiaki
Published: July 2007

The “photo‐excited” DLTS using light with energy less than the bandgap gives different spectra from the majority carrier DLTS spectra. This is because the transient response magnitude P(T) depends on temperature and the conventional DLTS analytical method cannot give correct activation energy Et and capture cross‐section σt for the deep levels. Herein the temperature‐dependence of P(T) is considered and the methods for obtaining Et and σt for minority carrier traps from the photo‐excited DLTS spectra have been proposed. These methods have been applied and found suitable to the derivation of Et and σt of the Fe‐level in a GaAs p+n junction and by comparing the results with those from the injection DLTS, its appropriateness is confirmed. Also the detection sensitivity and measurable levels are given as functions of the incident light energy. When these are compared and checked with the conventional DLTS method, the photo‐excited DLTS has been established as a measurement approach of minority carrier traps.
A new switched‐capacitor transformer and its analysis
Authors: Inoue Takahiro , Ueno Fumio , Oota Ichirou
Published: July 2007

IC realization of a switched‐capacitor transformer with in integer turn ratios, based on alternating and switching series and parallel‐connections of capacitors is presented. The circuit consists of n capacitors and 3n+1 MOS FET switches. This circuit is advantageous in that it has monolithic IC capability, DC voltage step‐up and step‐down are possible and non‐grounding can be achieved. It is thus useful for the integration of difficult circuits containing transformers. In this paper theoretical analyses are given for the case of ideal capacitors and switches, and for the case of non‐zero stray capacitance and on‐resistance. The effects of the on‐resistance of switches on the transfer characteristics of the transformer on the operating frequency range, allowable input level, element sensitivity and temperature characteristics are shown both theoretically and experimentally. As an example of applications, the test of a first‐order all‐pass filter is presented. The test used two 1,000pF capacitors and MOS FET switches; voltage step‐up and step‐down in the range from DC to 100 kHz were demonstrated. In this case the maximum allowable input level is about 0.5V and stability is ensured at temperatures from −20 to 80°C.
Experiment of a hybrid‐type implementation of an adaptive array under directional constraint
Authors: Takao Kazuaki , Kawamura Osamu , Komiyama Koji , Hashimoto Kozo , Kimura Iwane
Published: July 2007

The VHF 2‐channel adaptive antenna system was constructed by means of the output minimization under directional constraint, and its performance was evaluated. In the field experiment, the preservation of the desired signal and elimination of the interference wave were confirmed. The system adopts a hybrid‐type implementation of the analog processing part and digital processing part. The correlation between the input and output is calculated by the analog portion and the remaining computation is made by the digital portion. The time variation of the desired signal and the interference component, the frequency spectra of the output and the antenna directivity were measured in the laboratory. When the desired signal and the interference wave have the common frequency band, the interference wave can be suppressed sufficiently by this system if their incoming directions differ. The signal‐to‐interference ratio was above 30 dB. In the field experiment, we obtained 20 dB.
Circuit design of large scale dynamic MOS RAM with scaling relationships
Authors: Nagayama Yasuji , Yoshihara Tsutomu , Nakano Takao , Gamou Yoshimi
Published: July 2007

Further integration of the dynamic MOS RAM (MOS(D)RAM) depends on improvements in fabrication and in device and circuit techniques. To attain better operating characteristics and stable operation for large‐scale integration, it is necessary to establish a design approach that combines all of these techniques. This paper describes such an approach. First, the coefficientmdefining the sensitivity, read‐voltage and the operating region of the sense circuit is established and the design guidelines of the sense circuit are then derived. Analysis of the coefficientmshows that variations in device parameters attributable to processing accuracy significantly affect the stability of the large‐scale MOS(D)RAM operation. To obtain a wide operating region for the 64K MOS(D)RAM, the 128 refresh method is shown to be advantageous. Next, based on the design guidelines it is shown experimentally that 64KMOS(D)RAM can be fabricated with wide upper‐ and lower‐operating limits and that the design approach to large‐scale MOS(D)RAM using the fine‐pattern fabrication technique presented here is indeed valid.
Network recognition for VLSI mask pattern data
Authors: Fujiki Kunimitsu
Published: July 2007

Network recognition processing for obtaining circuit connections from mask data (mask pattern) is a keystone of test processing in order to obtain complete mask data before manufacturing IC. In this paper, we describe an algorithm to process trapezoidal mask data which are accurately processed in network recognition processing, a mask patch processing method in which part (mask patch) of the large‐scale mask data that is covered by a newly introduced patch figure is independently processed, and a comparison processing method which uses the decomposed region of the mask patch, and the equation to estimate the processing time from the number of the input mask data.

By using the mask patch processing method, restriction of the number of input mask data is alleviated, the processing time and the memory needed for processing are decreased, and, at the same time, flexibility for interrupting the operation is enhanced. The processing time of the proposed method is proportional to the number of input mask data. The processing time of applying the proposed method to a 16 k bit dynamic RAM mask data with 608080 mask data and 369962 elements is about 2.2 CPU hours on ACOS/700 computer, and shows good agreement with the estimated processing time, 2.3 hours, from the equation.
Multielement distributed coupled‐line constant‐resistance circuit with frequency multiplication characteristics
Authors: Sakagami Iwata , Suzuki Masatoshi , Miki Nobuhiro , Nagai Nobuo , Hatori Kozo
Published: July 2007

The microwave‐band distributed‐parameter constant‐resistance π‐type circuit composed of multistage two‐wire coupled lines and three resistances can be used as frequency multipliers which generate clock pulses 1010,…, 1–1, 1–1,…. The realization condition is discussed in this paper. The n‐section coupled line is represented by the equivalent signal flow graph where the delay line is considered delay element z−1. The transfer function in the z‐region is expressed by reflection coefficients at each section alone. The frequency‐multiplying circuit presented in this paper is composed of passive elements alone and is free from the external temperature variation. The experimental example is presented to confirm the validity of the theory.
Algorithms of two‐dimensional image identification and restoration based on an extended stochastic semi‐causal image model
Authors: Mizutani Hiroshi , Sugimoto Sueo
Published: July 2007

This paper is concerned with a new digital processing approach for restoration of additive‐noise‐corrupted images without using a priori statistical information concerning the autocovariance function of the original image field and the variance of noise.

Based upon an extended stochastic semi‐causal image model, the method mainly contains two algorithms of image identification and estimation. The algorithm for image identification consists of maximum‐likelihood estimation of unknown parameters and determination of the optimum image model by an information criterion (AIC). Furthermore, recursive Kalman estimation techniques are applied to restore the noise‐corrupted images.
Experiments on the broad‐band operation of stripline Y circulators loaded with a pair of coaxially combined Bi‐ferrite composites
Authors: Nagao Tsukasa , Tanaka Zengo , Umatani Kenji
Published: July 2007

Wideband operation of a stripline Y‐circulator has been realized below resonance with a coaxially combined two‐layer composite ferrite of nonuniform thickness. The composite ferrite (henceforth referred to as the composite element) consists of a thick ferrite disk with high saturation magnetization and a thin ferrite ring with low saturation magnetization. The circulator consists of tapered striplines and a composite element installed in a stripline Y‐junction and is operated with a uniform applied magnetic field. The insertion loss is less than 0.6 dB and the relative bandwidth is greater than 40% for 20 dB isolation. Circulation takes place at 4–5 different frequencies and is wideband. The paper describes the resonant mode characteristics, the relation between the Y‐junction shape and coupled line width and the structural factor of a composite element of nonuniform thickness.
Polarization characteristics of twisted single‐mode optical fibers
Authors: Namihira Yoshinori , Kudo Masaaki , Mushiake Yasuto
Published: July 2007

Because of complexity in the refractivity distribution of the twisted optical fiber, the theoretical study on the polarization characteristics is difficult. Therefore an experimental investigation is made first. A simple model is proposed to explain generation of cross‐polarization components in case of linearly polarized wave incidence. A generalized tensor permittivity applicable to a twisted elliptic‐core fiber is derived. For the circular‐core fiber, the off‐diagonal elements of the tensor have the θ‐z component ϵθz only. For the elliptic‐core fiber, both the r‐θ components ϵrθ and the r‐z component ϵrz appear as the off‐diagonal components. The polarization characteristics are analyzed by combining the even and odd modes of HE11 mode which is a fundamental mode in the single‐mode optical fiber.
Image reconstruction of long‐wavelength holograms by digital filter technique
Authors: Yamamoto Tsuyoshi , Aoki Yoshinao
Published: July 2007

A digital filter is used to reconstruct images from Fresnel‐transformed holograms by directly performing an inverse Fresnel transform with respect to a fixed plane which is defined by special parameters of propagation. In sampling holograms at the sampling interval Δx, the sampled propagator becomes a periodic function for sampling number N at distance 3p. An efficient digital filter can be constructed when N is an even squared number. The present method is also applicable to the hologram constructed at the propagation distance other than 3p if a corrected phase function is used. According to the computer simulation for comparison with other methods, the images reconstructed by the present method are as good as that by the one‐time Fourier transform method. This digital filter technique requires more computation than the FFT method, but it allows effective parallel processing and fast hardware realization.
A design method of super‐wideband pulse amplifiers
Authors: Ohue Kenji , Tsuyuki Shigeru
Published: July 2007

Super‐wideband amplifiers have become necessary in order to realize super‐highspeed digital transmission above 1 Gbit/s. In this paper a super‐wideband amplifier is realized based on a design method which makes practical use of the voltage gain and input impedence peaking effect due to the excessive phase shift of transistor. First, a single‐stage transistor unit amplifier is taken as a basic building block. These individual stages are then combined so as to simplify the design method. It is shown that the most suitable circuit for realizing wideband characteristics is that of voltage‐feedback unit amplifiers in cascade and with flattening circuits of parallel CR in the front. Also, from experiments using packaged bipolar transistor (fT = 10GHz), the characteristics of 4.3GHz high‐band cutoff frequency and 31 dB (6.2 dB per stage) are obtained.
Balanced helical antenna with tapered open ends
Authors: Yamauchi Junji , Nakano Hisamatsu , Mimaki Hiroaki
Published: July 2007

Radiation characteristics of a balanced helical antenna with tapered open ends operating in both polarizations are described and compared with those of a balanced uniform helical antenna (UH). The effect of the taper which heretofore has been treated only experimentally, is evaluated numerically in detail. First, using an integral equation with a simplified kernel, we derive the current distributions on an arm with 4 to 10 turns of windings. Next, we calculate the radiation characteristics from the current distributions thus obtained. We find that variations of the axial ratio are small when the gain is almost equal to that of the UH. From the frequency characteristics over 2.6 to 4.5 GHz, we find that the suppression of the reflected current at the tapers is maintained over a wide bandwidth. From the theory and experiment, the fluctuation of the input impedance vs. the frequency is smaller than that in the UH. Due to the taper at the open ends, degradation of the axial ratio in the UH at high frequencies is removed.
Low‐distortion GaAs varactor diodes
Authors: Hara Tohru , Niikura Ikuo , Toyoda Nobuyuki
Published: July 2007

Since a GaAs varacter diode has higher Q than a Si diode, it has been widely used for microwaves. This diode must have a hyper‐abrupt junction so as to cover a wide frequency band. However, there are technical limitations in the case of GaAs and up to the present it is realized by the double epitaxial growth method. It has been clear from measurement that diodes fabricated by the double epi‐method gives rise to large nonlinearity of capacitance with respect to voltage, which causes waveform distortion and cross‐modulation. In this paper the low‐distortion feature of a GaAs hyper‐abrupt junction diode using the novel multiple Siion implantation technique will be presented. A detailed device design for low distortion as well as the fabricated diode characteristics will be given.
Foundations on the realization theory of two‐dimensional arrays
Authors: Matsuo Tsuyoshi , Hasegawa Yasumichi , Niinomi Shigeru , Togo Makoto
Published: July 2007

Realization theory for non‐linear systems is now quite firmly established. As an application of the theory a problem in figure realization, representing a new kind of realization problem, is considered. The problem is to find the necessary and sufficient system of rules for reconstructing a given figure (two‐dimensional array). The commutative linear representation system is considered to provide the set of rules for generating the figure. The array realization theorem can be stated as follows. For any given array there exist at least two canonical commutative linear representation systems which realize the array, and any two canonical commutative linear representation systems are isomorphic. Circumstances requiring computer treatment of figures are becoming more frequent. The theory of array realization presented in this paper can serve as a basis for figure coding theory. Examples are given of the behavior (figures) of one‐dimensional and two‐dimensional commutative linear representation systems, and the relation between the commutative linear representation system and the two‐dimensional system is discussed.
On interleaved codes for error‐correcting codes
Authors: Ohkubo Masaya , Imai Hideki
Published: July 2007

Interleaving for error‐correcting codes is a method of composing a long‐burst‐error‐correcting code with combined short‐burst‐error‐correcting codes or random‐error‐correcting codes. The method is now employed in a wide variety of fields, such as communications, memory systems and PCM recording and is quite useful in increasing the reliability of such systems. However, there has been no detailed theoretical study of interleaving, although it has been the subject of numerous practical studies. A systematic study of its theoretical aspects and some new interleaving techniques are presented here. It is shown that, according to their construction, interleaved codes can be classified into the complete‐block type, convolutional type and incomplete‐block type, among which the incomplete‐block type is newly proposed. Other classifications of interleaving methods are made according to their types and numbers as well as their decoding methods. Next we review different trends in interleaving relevant to the types of codes to be used as the number of codes is changed. We then discuss an interleaving method with codes encoded by word units as well as an error‐detection code conduct a comparative investigation of the error‐correcting capability and encoding capability and encoding complexity as well as decoding from the viewpoint of construction. It is then shown that the incomplete‐block structure has an intermediate position between the complete‐block type and the convolutional type.
Design method of monolithic crystal filters having phase inverting auxiliary electrode
Authors: Kobayashi Masaki
Published: July 2007

Nuch has been reported on the analysis and design of the quartz monolithic crystal filter (MCF). Since the mechanical coupling between contiguous energy trapping resonators is dependent on the cutoff mode, the propagation phase is independnet of the resonator spacing. This paper analyzes the MCF with phase inverting electrodes and establishes a design method for solution to the above restriction. First, we derive an approximation to the resonator coupling coefficient and compare the effect of the phase inverter on the center frequency of the filter with rigorously obtained data. Next, we study the effect of unwanted modes on the transfer characteristics of the filter. Finally, we describe the design method and compare the data with experimental values. The optimum values of the width of the phase inverter and of the decrease in frequency are given in terms of the resonant frequency and the frequency reduction of the resonator. These relations are summarized in graphical form to facilitate the design. The phase inverter tends to increase the center frequency of the filter and the amount of increase must be taken into account in the design stage. By studying the transfer characteristics of the MCF based on the present design procedure, we can improve the symmetry of the attenuation in the stopband.
Design of E‐plane cosecant square beam horn antennas based on ray theory and their radiation characteristics
Authors: Sha Kokusho , Suzuki Michiya , Nakata Waichi , Adachi Saburo
Published: July 2007

A new method of analyzing and designing a nonplanar aperture‐type E‐plane cosecant square beam horn antenna is proposed. This new method is based on the ray theory. The experimental results show that the computed radiation patterns are in good agreement with the measured patterns. This proposed method enables one to design a high‐gain cosecant square beam horn antenna of simple structure with E‐plane sectional horn whose aperture length is about 12 wavelengths.
Impulse response of contradirectional couplers
Authors: Takai Shuuetsu , Mishima Teruhito , Sakuraba Ichiro
Published: July 2007

This paper discusses the impulse response of optical components such as contradirectional couplers and corrugated waveguide filters. The analysis is based on the coupled mode theory which utilizes the main forward and backward modes in the absence of higher harmonics.

The impulse response of the forward and backward modes is derived in a form corresponding to repeated reflections at two ends of the system. As for the backward modes, the behavior of reflected waves is related to the coupling length. The impulse responses of transmitted and reflected waves are derived and their pulse responses are analyzed by the convolution integral.
Computer simulated reproduction process with nonlinear magnetic heads
Authors: Koshimoto Yasuhiro , Mikazuki Tetsuo
Published: July 2007

To upgrade magnetic recording equipment consideration anticipated is given to the construction of an electromagentic conversion using high‐permeability magnetic media in order to obtain high output with high resolution power. In the case of obtaining high reproduction output, the nonlinear magnetism of the reproduction head can affect the reproduction properties, but presently there is no report on the head operation with nonlinearity taken into account. In this paper, the reproduction process with nonlinear magnetic head is simultaed numerically and the magnetic field, permeability and magnetic flux distributions in the head as well as the effect of the nonlinearity of the head core material are analyzed. Results show that the core permeability decreases locally because of local concentration of magnetic flux due to the presence of recorded media and the permeability decreases significantly when the medium position giving rise to maximum output lies in the vicinity of the gap. The reason for degradation of the reproduction characteristics in heads using material with low saturation flux density can be explained by the fact that the low‐permeability region in the vicinity of the gap gives rise to an effective gap increase.
A design of back‐feed type circularly polarized microstrip disk antennas having symmetrical perturbation element by one‐point feed
Authors: Haneishi Misao , Yoshida Shinichiro , Tabeta Masashi
Published: July 2007

A one‐point back‐feed type circularly polarized microstrip disk antenna is investigated. To establish a design procedure, (1) the operating condition for circular polarization is studied and design formulas and data are presented and (2) the fabrication and radiation characteristics of arrays consisting of the present circularly polarized disk antenna element are discussed. It is demonstrated that this class of antennas can serve as a useful form of circularly polarized array element. Further, in order to analyze the mutual coupling of such antenna elements, the resonance and inter‐element mutual admittance of an array consisting of two disk antennas located on the same plane are determined. The fundamental information on the mutual coupling thus obtained is presented for a design aid. Using these results, a circularly polarized array is realized with good axial ratio and boresight ratio less than 0.5 dB.
Perturbation analysis of corrugated dielectric waveguide with application to millimeter‐wave filters
Authors: Ohira Takahashi , Tsutsumi Makoto , Kumagai Nobuaki
Published: July 2007

The propagation characteristics of the TM mode wave in a two‐dimensional dielectric slab with a sinusoidal corrugation are theoretically analyzed. A coupled‐mode equation is derived for describing the coupling between the forward and backward waves near Bragg frequency caused by the corrugation and the Brillouin diagram is clarified. The theoretical characteristics of the reflection filter made of a dielectric slab with a finitely long corrugation are investigated. Using a Teflon slab loaded with a rectangular corrugation, experiments are conducted on the reflection filter in the 40‐GHz band and the results are compared with theoretical values. It is found that such filter characteristics as the Bragg frequency, return loss and stopband half‐width agree well with theoretical predictions.
Analysis of coplanar striplines on an anisotropic substrate using Galerkin's method
Authors: Hayashi Yoshio , Kitazawa Toshihide , Sasaki Shinji
Published: July 2007

A unified analysis approach is shown for obtaining the quasistatic and dispersive characteristics of coplanar Striplines on a uniaxial anisotropic substrate. Galerkin's method is adopted in the numerical calculations and the basis functions are determined systematically by use of Chebyshev polynomials with the result that solutions with desired accuracy can be obtained efficiently. In general, in coupled striplines large errors occur when the current distribution function is to be determined solely by its fringing effect. In the case of sapphire substrate, the accuracy of solution is investigated and its propagation wavelength as well as characteristic impedance are obtained and shown in graph. In these graphs the quasistatic characteristics obtained from the electrostatic approximation and the hybrid mode dispersion are compared so that a rough criterion of the error due to the electrostatic approximation can be estimated. The quasi‐static characteristics of a uniaxial anisotropic substrate line can be characterized by its effective and equivalent isotropic substrate [1]. The dispersion of the isotropic substrate line is obtained and compared with that of the original anisotropic line.
Automatic laser radar systems for measurement of atmospheric pollutants
Authors: Kimura Hiroichi , Shimada Takashi
Published: July 2007

Laser radar employing the Mie scattering principle for monitoring atmospheric pollutants has been widely used because of its capability of remote measurement of the distribution of aerosols. For practical purposes, however, the accuracy, measurable range and quantitativeness of measurement have been major drawbacks in conventional systems. In order to overcome such drawbacks and increase the practicality, a laser radar system with computer automatic measuring and data processing functions has been developed. In this system the Mie‐scattered signal is quantified so as to represent the dust concentration and the signal‐to‐noise‐ratio is improved by employing an averaging process. Four standard methods of measuring the three‐dimensional distribution of the dust concentration are presented. According to field test results, averaging process proves to be quite effective and the measured values obtained by the system agree well with those obtained by a conventional digital dust concentration indicator. By examples of the measurement of dust concentration at various altitudes the system is shown to be useful not only for the study of atmospheric pollution but also for the continuous monitoring and forecasting of pollution.
Approximate representations of a class of nonuniform lines based on approximate mixed lumped‐distributed representations of linear taper lines
Authors: Kobayashi Kunikatsu , Nemoto Yoshiaki , Sato Risaburo
Published: July 2007

The nonuniform line containing the binomial‐form transmission line of odd order can be approximated by the lumped‐distributed circuit at frequencies below π/2 (rad) in electrical length. The rigorous solution for telegraph equation of odd‐order binomial‐form lines with the characteristic impedance given by (ax±b)±n (where a and b are constant and n is odd number) is derived and the approximate solution is obtained for a case where four‐terminal constants of the linear taper line with n=1 are truncated at finite terms. It is shown that the linear taper line can be approximated by the lumped‐distributed circuit at frequencies below π/2 (rad) in electrical length. Next, Kuroda's identity is applied to the lumped nonuniform distributed circuit consisting of the linear taper line and lumped reactance to show that the nonuniform line containing binomial‐form transmission lines can be obtained as a cascade connection of the linear taper line and lumped reactance. Finally, the nonuniform line is approximated by the lumped‐distributed circuit at frequencies below π/2 (rad).
Computation of periodic solutions for polynomial nonlinear equations
Authors: Kawakami Hiroshi , Kobayashi Kunihiro
Published: July 2007

The periodic solution of polynomial nonlinear equations is derived based on Galerkin's procedure. An algorithm for evaluating deterministic equations and elements of Jacobian matrices is presented. This algorithm enables one to determine a periodic solution and to reduce the computation time and procedure. The result is applied successfully to periodic solutions of Duffing's equation, Van der Pols' equation, the pendulum equation, Minorsky's equation, the population growth model with time lag and the difference equation.
Measurement of millimeter‐wave reflection coefficients by using a T‐junction
Authors: Iwasaki Takashi , Nagatsuka Akio , Nemoto Toshio
Published: July 2007

A technique of measuring millimeterwave reflection coefficients by using a T junction is proposed. This technique does not require a tuning procedure and frequency conversion. The measurement circuit is composed of a T junction and power meter, where system constants of the circuit are calibrated in advance by using a sliding short. The standard waveguides are used to shift the phase angle of the reflection coefficients of a load under test and the unknown reflection coefficient is computed from the powermeter reading. The measurement result at 34.0 GHz indicates the validity of this technique. The error was estimated as about 2.7% at the 0.3 magnitude of the reflection coefficient.
An analysis of a CVS multiberth station model via markov renewal theory
Authors: Kurihara Masahito , Kaji Ikuo , Nakada Katsuhiro
Published: July 2007

A stochastic model has been developed for a CVS (Computer‐controlled Vehicle System) station with multiple parallel berths. In this model to study the effects of the number of berths on the behavior of a station, the following simplification is made in contrast to the conventional single‐berth station models. That is, loading and unloading times for each berth are assumed to follow the same exponential distribution regardless of the vehicle type, and the vehicle departure condition does not depend on the vehicle either. This type of model is formulated as a Markov renewal process and analyzed. As a result we have clarified the fundamental relationships between the number of berths and measures for evaluating a station such as the expected interval time of entrances, the departure rate, the entrance factor and the utilization factor of berths. Also, by examining the asymptotic characteristics of the expected interval time of entrances we have found the fundamental differences between a single berth station and a multiberth station, we have shown trade‐offs between the entrance factor and the departure rate and we have investigated the implications of increasing the number of berths. On the other hand, by simulations with a normal loading and unloading time distribution, we examined the effectiveness of the results of this paper for which an exponential distribution was assumed for the loading and unloading times.
An adaptive digital filter as a sinusoidal noise canceller
Authors: Ohmuro Takashi , Tachibana Yasuo
Published: July 2007

An adaptive filter is capable of varying its parameters adaptively in response to change in the characteristics of noise components. Thus it is effective for filtering out the nonstationary noise. This paper proposes an adaptive moving average filter (AMAF) for the extraction of desirable signal from the mixture of low‐frequency signal, white noise and narrowband sinusoidal noise. The implementation of AMAF is simply an extension of a moving average filter, and therefore is easy to implement and yet very effective for sinusoidal noise removal. As a special case, when the desired signal is a sinusoidal waveform, the design characteristics such as the noise attenuation index and the distortion rate of the AMAF are evaluated via computer simulation. The simulated results match the results obtained through theoretical analysis.
Design and performance of interference cancellation circuit
Authors: Kaitsuka Toshiyuki , Inoue Takeo
Published: July 2007

This paper presents an interference cancellation circuit based on a side‐lobe canceller. A new interference canceller is investigated in which the receiving interference signal of the auxilary antenna is modulated by a low‐frequency signal. When this signal is combined with the main antenna receiving signal, envelope detection is used and the error voltage of the interference canceller will be obtained from the detection of the low‐frequency signal and the phase. The interference cancellation effect is measured. The results show that above suppression ratio above 40 dB over a band‐with of 50 MHz can be achieved regardless of whether the signal is CW, FM or PSK or the undesired and desired signals are co‐channel signals. For a PSK signal even with D/U = −10 dB prior to cancellation, the bit error rate after cancellation can still be maintained equal to that without interference at all. Also a good suppression ratio can even be achieved in outdoor situations and the circuit presented here has obvious practical value.
Computer analysis of microwave planar circuit with impedance matrix
Authors: Jui‐Pang Hsu , Anada Tetsuo , Kaneko Hitoshi
Published: July 2007

Computation of the wideband frequency characteristics of a microwave planar circuit with arbitrary shape requires computer processing because there are many parameters involved. However, if numerical calculations are carried out by computer from beginning to end, it is difficult to detect the amount of error and the error locations. The present paper resolves this problem. In addition conventional network theory is applied to the planar circuit and a computational method for easy understanding is introduced. To this end, the mode impedance looking at the planar circuit from the transmission line is defined Using this mode inpedance, network theory is employed to derive an expression of the effective impedance of the planar circuit projected on the dominant mode of the transmission line. Once the effective impedance is given,the frequency characteristics (S‐matrix) of the circuit can be computed over a wide frequency range. A computer program is developed for this procedure and applied to the analysis of a corner‐cut right‐angle bend. Potential problematic points of the program are discussed. It is also found that the optimum cut of the right‐angle bend can be computed and that the results so obtained agree with those known to date. Finally, it is pointed out that the present method is not only effective for the analysis of planar circuits, but also permits the analysis of higher‐order modes of planar circuits.
Optimum spatial filter for optical defocus sensing
Authors: Takemura Kohji , Tsutsumi Suteo
Published: July 2007

Spatial filters for optical defocus sensing are discussed. The transfer function of the optimum spatial filter is derived from the condition that the gradient of the output with respect to the defocus distance is maximum. As an example of near‐ideal, physically realizable spatial filters, a plus‐minus checkerboard detector array is proposed. Dimensions of the detector elements for the checkerboard array are discussed in relation to the blur circle which is determined by factors other than defocusing, such as aberrations. Furthermore, a complex plus‐minus checkerboard reticle is proposed with a view to the wide range of Wiener spectrum of the input scenes from white spectrum to color spectrum. Experiments carried out using a plus‐minus checkerboard reticle demonstrated the capability of defocus sensing for a representative input scene, and the feasibility as a relatively short range finder.
Error probability analysis for multilevel digital signals in nonlinear channels
Authors: Okamoto Eiji
Published: July 2007

In digital microwave communication, the signal power is first amplified and then transmitted. However, power amplifiers have, in general, nonlinear characteristics. If such an amplifier is used in a linearly modulated tranmission system, the signal is subjected to nonlinear distortion. This makes analysis of the channel extremely difficult. If the number of levels in the transmission channel is few, the method of simulation can be applied for analysis. If the number of levels is large, the calculation becomes unwieldy. In this paper a simple analytical method to compute the intersymbol interference distribution and error probability of the output signal for a nonlinear transmission channel consisting of an amplifier with assumed cubic approximation for the input‐output characteristics, a transmitter filter and a receiver filter. This simplicity, derived from the fact that small intersymbol interference can be regarded as Gaussian noise in the aggregate, becomes the theoretical base. Also, the validity of the method is shown in comparing the error probability of the 4‐ary PSK system computed from the proposed method with that obtained by the simulation method.
Studies on the URN scheme for multiple access packet communication systems
Authors: Fukuda Akira , Hasegawa Yuji
Published: July 2007

Research on random‐access systems has been mainly based on the ALOHA system. However, such systems have an inherent risk of channel saturation due to the avalanche phenomenon of retransmitted packets. Therefore, several access systems, such as the URN scheme, have been proposed with consideration of adaptability to operational stability and load variation. In this paper we conduct a detailed study of the characteristics of the URN scheme, which is quite attractive in using the concept of direct access instead of random delay. Particularly, we study the influence of errors in estimating the number of packets awaiting transmission and the number of working terminals. It is concluded that these estimations need not be highly accurate. We then propose the H‐URN scheme, which has a slight overhead allowance for state estimation and is simply realizable. It will also be shown that the system characteristics are only slightly degraded compared with the ideal case. Further, the optimally controlled ALOHA system is studied with similar assumptions and methods and it is concluded that the URN scheme is superior in many respects. In addition, brief consideration will be devoted to several points which have not been studied sufficiently (e.g., problems of Ack and comparison with the TDMA system).