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[Keyword] magnetic(575hit)

301-320hit(575hit)

  • Estimation of Multiple Coherent Source Locations by Using SPM Method Combined with Signal Subspace Fitting Technique

    Yuzo YOSHIMOTO  Kazumasa TAIRA  Kunio SAWAYA  Risaburo SATO  

     
    PAPER-Measurements

      Vol:
    E88-B No:8
      Page(s):
    3164-3169

    A visualization method of coherent source locations based on the Sampled Pattern Matching (SPM) method is described. Modified SPM method is proposed to improve the S/N, in which the measurement of the electric field distribution is repeated in appropriate time duration and eigenvalue decomposition of the covariance matrix is introduced. A combination of the modified SPM method with the Weighted Subspace Fitting (WSF) method is also proposed to estimate accurate source locations. A calibration technique by using a reference antenna to compensate the complex pattern of the receiving antenna is proposed. Experimental investigation to estimate source location for one dipole antenna and two dipole antennas is also made to demonstrate the validity of the proposed method.

  • Evaluation of Damage in DNA Molecules Caused by Very-Low-Frequency Magnetic Fields Using Bacterial Cells

    Akira HAGA  Yoshiaki KUMAGAI  Hidetoshi MATSUKI  Ginro ENDO  Akira IGARASHI  Koichiro KOBAYASHI  

     
    PAPER-Biological Effects

      Vol:
    E88-B No:8
      Page(s):
    3249-3256

    The effect of intermediate frequency magnetic fields or, very-low-frequency magnetic fields (VLFMF) on living biological cells was investigated using a highly sensitive mutagenesis assay method. A bacterial gene expression system for mutation repair (umu system) was used for the sensitive evaluation of damage in DNA molecules. Salmonella typhimurium TA1535 (pSK1002) were exposed to VLFMF (20 kHz and 600 µT) in a specially designed magnetic field loading chamber. The experiment results showed the possibility of applying the umu assay for sensitive and effective evaluation of damage in DNA molecules. No effects from exposure to 20 kHz and 600 µT magnetic fields in terms of damage in DNA molecules were observed.

  • Investigation on the Dynamic Characteristics of a Magnetic Release in Molded Case Circuit Breaker

    Honggang XIANG  Degui CHEN  Xingwen LI  Zhipeng LI  Weixiong TONG  

     
    PAPER-Contactors & Circuit Breakers

      Vol:
    E88-C No:8
      Page(s):
    1647-1651

    A method is proposed to investigate the dynamic characteristics of a magnet release in molded case circuit breaker. With the static field assumption, two grids of the magnetic torque and flux linkage are calculated with the variation of the current and air gap, firstly. Considering the influence of tripping torque, coupled with circuit equation and mechanism motion equation, the dynamic characteristics may be obtained with Runge-Kutta 4 method. Experiments have been done to verify the method, and the difference between the calculated results and the experimental results is below 10%. In addition, the influence of the reaction spring on the protection characteristics is analyzed using this method. It demonstrates that the setting current varies with the initial angle and the stiffness of the reaction spring, and the variation with the initial angle of the reaction spring is closely linear but the stiffness nonlinear.

  • Invasiveness of an Optical Magnetic Field Probe

    Satoru ARAKAWA  Eiji SUZUKI  Hiroyasu OTA  Ken Ichi ARAI  Risaburo SATO  

     
    PAPER-Measurements

      Vol:
    E88-B No:8
      Page(s):
    3170-3175

    Electromagnetic field probes inevitably disturb the original distribution of the field when they are positioned close to a device. This disturbance in turn affects measurement accuracy and device operation. We developed an optical magnetic field probe, comprising a loop antenna element and an electro-optic crystal, for highly accurate magnetic near-field measurement in the GHz frequency range. We analyzed the invasiveness of the optical magnetic field probe quantitatively both experimentally and using finite difference time domain simulation. We found that eliminating the metal cable reduced the disturbance of the surrounding field that was to be measured. In addition, we investigated the magnetic field detection characteristics of the probe and its influence on the operation of a microstrip line. The optical magnetic field probe was less invasive and provided more accurate measurement.

  • Experimental Study on Compensation of Array Element Pattern of Collinear Dipole Array Sensor

    Kyosuke AWAI  Kazumasa TAIRA  Kunio SAWAYA  Risaburo SATO  

     
    LETTER

      Vol:
    E88-B No:8
      Page(s):
    3314-3316

    A compensation method of the array element pattern is proposed to measure EM field distribution on an observation plane located several wavelengths away from electronic devices in a short time. Numerical and experimental data of the 3 and 5 element collinear dipole array sensors are presented to demonstrate the validity of the proposed method.

  • Characteristic Analysis and Enhancement of Sensing Property for Eddy-Current Type Proximity Sensor

    Koichi KOIBUCHI  Koichiro SAWA  Takashi HONMA  Takumi HAYASHI  Kuniyoshi UEDA  Hiroshi SASAKI  

     
    PAPER-Sensing Devices

      Vol:
    E88-C No:8
      Page(s):
    1696-1703

    An eddy-current type proximity sensor is a non-contact type sensing device to detect the approach of a conductor by increase of equivalent AC resistance of excitation coil due to eddy current loss in the conductor. In this paper, electromagnetic characteristics of the actual proximity sensor are calculated by FEM and the validity of numerical analysis results are studied. Furthermore, two models that has modified magnetic circuit geometry based on the actual sensor are designed and calculated as numerical experiments. Calculated results are shown as enhanced sensing index or electromagnetic characteristics of the modified sensor. In conclusions, knowledge about the magnetic circuit geometry of the sensor is applied for the enhancement of sensing property.

  • PCB Structure with a Guard Band for Suppressing Electromagnetic Radiation

    Yoshiki KAYANO  Motoshi TANAKA  Hiroshi INOUE  

     
    PAPER-Printed Circuit Boards

      Vol:
    E88-B No:8
      Page(s):
    3182-3188

    Electromagnetic (EM) radiation from a feed cable attached to a printed circuit board (PCB), which is commonly encountered electromagnetic interference (EMI) problem at high-speed electronic PCB designs, is investigated by experimental and finite-difference time-domain (FDTD) modeling. In this paper, we propose and demonstrate a guard-band structure as a method for suppressing the EM radiation from a PCB with a feed cable. A signal trace is located between two ground traces (guard-band: GB). Four different cross-sectional PCB structures, which are commonly used in microwave integrated circuits as typical structures, are used to compare the guard-band structure. Frequency response of common-mode (CM) current, electric field near a PCB, and far electric field (radiated emission) are investigated as characteristics of the EMI. Results show that the shield structure is effective in suppressing the CM current at lower frequency. However, structures in which a conductive plate exists near the signal trace yield resonances with high level peak on CM current, near and far-field. On the other hand, the guard-band structure is more effective than other structures in suppressing the EM radiation in the considered frequency range. Therefore the guard-band will be effective for high-density PCB packaging with high-speed traces.

  • APD Measurement for Evaluating Disturbances Related to the Performance of Digital Communication Systems

    Kaoru GOTOH  Yasushi MATSUMOTO  Yukio YAMANAKA  Takashi SHINOZUKA  

     
    PAPER-Communications

      Vol:
    E88-B No:8
      Page(s):
    3235-3241

    The measured values of electromagnetic disturbances should strongly correlate with degradation in the communication quality of digital wireless communication systems. The Amplitude Probability Distribution (APD) of a disturbance represents statistical information as applicable measurement readings that meet the above requirement. In this paper, correlations between APD measurements of disturbances and the bit error rate (BER) as a quality degradation index for victim systems are quantitatively investigated. Disturbance regulation by APD measurements is discussed from the viewpoint of protecting systems from disturbances. This investigation specifically considers the situation in which a repetition pulse disturbance impacts PHS and W-CDMA systems assumed as victims. The results confirm high correlations between the APD and BER not only experimentally but also theoretically under some conditions. A disturbance regulation criterion based on APD measurements is thus proposed for compliance testing of electronic appliances with the potential to act as disturbance noise sources.

  • Radio Wave Interference Test Method for Wireless Communication System by Opened Parallel Wired Cell

    Masamitsu TOKUDA  Kouhei ICHIKAWA  Yasuo HONMA  Masayuki KITORA  

     
    PAPER-Communications

      Vol:
    E88-B No:8
      Page(s):
    3242-3248

    We have studied on the interference test method from IEEE802.11b to IEEE802.11g as an interference source with wide band spectrum by using the opened PW cell, and it is clear that the throughput of IEEE802.11g for only IEEE802.11b Ch.4 signal wave as the interference wave, whose frequency spectrum is almost not overlapping with IEEE802.11g, is almost not interfered by IEEE802.11b, but the throughputs for all other channels from Ch.5 to Ch.8 as the interference wave are interfered and decrease to below 2 Mbps. By comparing with conventional radiated RF electromagnetic field immunity test specified by IEC 61000-4-3, it is clear that the conventional immunity test cannot simulate the interference phenomena from IEEE802.11b to IEEE802.11g. Next, we tried to perform the interference test of the Bluetooth against the wireless LAN IEEE 802.11b as a disturbance source. As a result, it is revealed that the throughput of Bluetooth decreases according to increasing the interference wave level, and communication between EUT (slave) and the master of Bluetooth is interrupted for the interference wave corresponding to Ch.7 (244210 MHz). However, in the conventional immunity test specified by IEC 61000-4-3, the throughput of the Bluetooth does not affect for the all disturbance waves corresponding to the center frequency of bandwidth on the cannel of IEEE802.11b. Therefore, it is needed for the wireless LAN and the Bluetooth to develop new radiated immunity test method, which has the disturbance wave with wide bandwidth.

  • Radiated Electromagnetic Field Immunity Test Method for Wireless LAN Using Opened Parallel Wired Cell

    Masamitsu TOKUDA  Masayuki KITORA  Yasuo HONMA  Kouhei ICHIKAWA  

     
    PAPER-Communications

      Vol:
    E88-B No:8
      Page(s):
    3229-3234

    We study radiated RF (radio-frequency) electromagnetic field immunity test system for wireless LAN system by using opened PW (Parallel Wired) cell, in which metal cover is removed. Leakage electric field at distance of 160 cm from the opened PW cell decreases until 30 dB, and then does not affect to operation of the AP (Access Point) composed of the wireless LAN system that communicates EUT (Equipment Under Test) installed in the PW cell. NSA (Normalized Site Attenuation) between EUT and AP changes only several dB by inserting the PW cell, and then it can be concluded that the effect of PW cell for radio wave property of wireless communication system is negligible small. In addition, we try to measure dependencies of impressing level of disturbance wave on a throughput of wireless LAN systems IEEE802.11b and IEEE802.11g. As a result, it is confirmed that the radiated RF electromagnetic field immunity test system for wireless LAN system can be composed by using the opened PW cell without affecting from impressing disturbance wave.

  • Correspondence of Common- and Differential-Mode Components on EM Radiation from Surface Microstrip Line Structure

    Yoshiki KAYANO  Motoshi TANAKA  Hiroshi INOUE  

     
    PAPER-Signal Transmission

      Vol:
    E88-C No:8
      Page(s):
    1688-1695

    It has been demonstrated that a common-mode (CM) current can dominate the EMI processes up to 1 GHz, despite the fact that a CM current is smaller than a differential-mode (DM) current. However, this description is insufficient to describe behavior above 1 GHz. In this paper, the correspondence of CM and DM components for total electromagnetic (EM) radiation from a printed circuit board (PCB) with surface microstrip line, which is commonly used in microwave integrated circuits, at gigahertz frequency is studied experimentally and with finite-difference time-domain (FDTD) modeling. In order to characterize the EM radiation, the frequency response of the CM current, the electric field near the PCB, and the electric far field are investigated. First, the frequency response of the CM current, near and far-fields for the PCB with an attached feed cable are compared up to 5 GHz. Although the CM current decreases above a few gigahertz, near and far electric fields increase as the frequency becomes higher. Second, in order to distinguish between CM and DM radiation at high frequency, the frequency response and the angle pattern of the far-field from a PCB without the feed cable are discussed. The results show that radiation up to 1 GHz is related to the CM component. However, depending on polarization and PCB geometry, radiation may be dominated by the DM rather than the CM component. The results indicate that the DM component may be more significant relative to the CM component, and the increase in EM radiation can not be predicted from only the frequency response of CM current. Therefore, identifying the dominant component is essential for suppressing the EM radiation. This study is a basic consideration to realize a technique which is effective on the suppression of the EM radiation from the PCB with an attached feed cable.

  • Noise Reduction for NMR FID Signals via Oversampled Real-Valued Discrete Gabor Transform

    Liang TAO  Hon Keung KWAN  

     
    PAPER-Adaptive Signal Processing

      Vol:
    E88-D No:7
      Page(s):
    1511-1518

    An efficient algorithm to reduce the noise from the Nuclear Magnetic Resonance Free Induction Decay (NMR FID) signals is presented, in this paper, via the oversampled real-valued discrete Gabor transform using the Gaussian synthesis window. An NMR FID signal in the Gabor transform domain (i.e., a joint time-frequency domain) is concentrated in a few number of Gabor transform coefficients while the noise is fairly distributed among all the coefficients. Therefore, the NMR FID signal can be significantly enhanced by performing a thresholding technique on the coefficients in the transform domain. Theoretical and simulation experimental analyses in this paper show that the oversampled Gabor transform using the Gaussian synthesis window is more suitable for the NMR FID signal enhancement than the critically-sampled one using the exponential synthesis window, because both the Gaussian synthesis window and its corresponding analysis window in the oversampling case can have better localization in the frequency domain than the exponential synthesis window and its corresponding analysis window in the critically-sampling case. Moreover, to speed up the transform, instead of the commonly-used complex-valued discrete Gabor transform, the real-valued discrete Gabor transform presented in our previous work is adopted in the proposed algorithm.

  • An X-Band Microstrip Phase Shifter Using an Electromagnetic Bandgap Backplane

    Dowon KIM  Moonil KIM  Hao XIN  Jon B. HACKER  

     
    LETTER-Devices/Circuits for Communications

      Vol:
    E88-B No:6
      Page(s):
    2632-2635

    A new microstrip compatible phase shifter circuit is introduced. The phase shifter uses a strip-type electromagnetic bandgap (EBG) substrate in place of the solid metal ground plane. Such EBG substrates, when made of ferroelectric materials, can produce variable phase constants useful for phase shifter applications. Test models using two different EBG substrates with dielectric constants of 9.2 and 10.2 showed 44.5 degrees of phase difference with 1.7 dB of added insertion loss at 10 GHz from a line originally 504 degrees long.

  • Antennas and Propagation in the Presence of Metamaterials and Other Complex Media: Computational Electromagnetic Advances and Challenges

    Richard W. ZIOLKOWSKI  

     
    INVITED PAPER

      Vol:
    E88-B No:6
      Page(s):
    2230-2238

    There have been significant advances in computational electromagnetics (CEM) in the last decade for a variety of antennas and propagation problems. Improvements in single frequency techniques including the finite element method (FEM), the fast mulitipole moment (FMM) method, and the method of moments (MoM) have led to significant simulation capabilities on basic computing platforms. Similar advances have occurred with time domain methods including finite difference time domain (FDTD) methods, time domain integral equation (TDIE) methods, and time domain finite element (TD-FEM) methods. Very complex radiating and scattering structures in the presence of complex materials have been modeled with many of these approaches. Many commercial products have been made available through the efforts of many individuals. The CEM simulators have enabled virtual EM test ranges that have led to dramatic improvements in our understanding of antennas and propagation in complex environments and to the realization of many of their important applications.

  • Antenna Design by Using Method of Moments

    Kunio SAWAYA  

     
    INVITED PAPER

      Vol:
    E88-B No:5
      Page(s):
    1766-1773

    The theory of the method of moments (MoM), which has been widely used as a numerical technique for analyzing the characteristics of antennas and scatterers, is described. First, the steps of MoM to solve integral equations for conducting wires and planes are presented. It is pointed out that MoM combined with Galerkin's method yields highly accurate results. The importance of ensuring the continuity condition of current on conducting bodies is emphasized and numerical examples for a conducting structure involving junctions of wire segments and planar segments are presented. Finally, MoM for dielectric scatterers including recent developments is described.

  • Antenna Design Using the Finite Difference Time Domain Method

    Toru UNO  

     
    INVITED PAPER

      Vol:
    E88-B No:5
      Page(s):
    1774-1789

    The finite difference time domain (FDTD) method has been developed in tandem with the progress of computer technology since K. S. Yee applied it to the analysis of an electromagnetic problem in 1966. The FDTD method is widely recognized as a powerful computational tool for analyzing electromagnetic problems involving complex geometries, such as antennas, microwave and optical waveguides and interaction between antennas and the human body. The commercial electromagnetic simulators based on the FDTD are also being developed very actively because users are able to trace temporal electromagnetic behaviors and to easily obtain a practical level of accuracy. However, the user must understand the principle of the method in order to use the simulator efficiently. In this paper, the basic concept and the principle of the FDTD method are reviewed for beginners, including graduate course students, rather than specialists in this discipline. Several recent topics concerning electromagnetic and antenna problems are also introduced.

  • Reduction of Electromagnetic Penetration through Narrow Slots in Conducting Screen by Two Parallel Wires

    Ki-Chai KIM  Sung Min LIM  Min Seok KIM  

     
    LETTER-Electromagnetic Compatibility(EMC)

      Vol:
    E88-B No:4
      Page(s):
    1743-1745

    This letter presents a reduction technique of penetrated electromagnetic fields through a narrow slot in a planar conducting screen. When a plane wave is excited to the narrow slot, the aperture electric field is controlled by the two parallel wires connected on the slot. The magnitude of penetrated electromagnetic fields through a narrow slot is controlled by electric field distributions on the slot aperture. The results show that the magnitude of the penetrated electromagnetic field can be effectively reduced by installing the two parallel wires on the slot.

  • Band-Limitation Effects on Microwave Oven Noise in the 2.4-GHz Band

    Yasushi MATSUMOTO  Takahide MURAKAMI  Katsumi FUJII  Akira SUGIURA  

     
    LETTER-Electromagnetic Compatibility(EMC)

      Vol:
    E88-B No:3
      Page(s):
    1307-1312

    Electromagnetic noise radiated from microwave ovens may cause serious interference problems in wireless systems using the 2.4-GHz band. Since oven noise waveforms show strong dependence on the frequency selectivity of the receiver filters, the effect of band limitation on the interfering oven noise is an important issue for evaluating or comparing the performance degradation of wireless systems subject to interference. To understand these effects, theoretical and experimental investigations of the waveform, peak amplitude, and pulse width of band-limited oven noise are carried out. It is found that the peak amplitude of the received noise changes with the bandwidth in a way very similar to the case of a simple RF tone-burst input. The pulse width of the received noise also changes with the receiver bandwidth but takes a minimum value at a certain receiver bandwidth, which is an essential feature of band-limited microwave oven noise. In addition, an appropriate resolution bandwidth is determined for using a spectrum analyzer to obtain accurate oven noise parameters.

  • Azim: Direction-Based Service System for Both Indoors and Outdoors

    Yohei IWASAKI  Nobuo KAWAGUCHI  Yasuyoshi INAGAKI  

     
    PAPER-Application

      Vol:
    E88-B No:3
      Page(s):
    1034-1044

    In this paper, we propose an advanced location-based service that we call a direction-based service, which utilizes both the position and direction of a user. The direction-based service enables a user to point to an object of interest for command or investigation. We also describe the design, implementation and evaluations of a direction-based service system named Azim. With this system, the direction of the user can be obtained by a magnetic-based direction sensor. The sensor is also used for azimuth-based position estimation, in which a user's position is estimated by having the user point to and measure azimuths of several markers or objects whose positions are already known. Because this approach does not require any other accurate position sensors or positive beacons, it can be deployed cost-effectively. Also, because the measurements are naturally associated with some degree of error, the position is calculated as a probability distribution. The calculation considers the error of direction measurement and the pre-obtained field information such as obstacles and magnetic field disturbance, which enables robust position measurements even in geomagnetically disturbed environments. For wide-area use, the system also utilizes a wireless LAN to obtain rough position information by identifying base stations. We have implemented a prototype system for the proposed method and some applications for the direction-based services. Furthermore, we have conducted experiments both indoors and outdoors, and exemplified that positioning accuracy by the proposed method is precise enough for a direction-based service.

  • Magnetic Marker and High Tc Superconducting Quantum Interference Device for Biological Immunoassays

    Keiji ENPUKU  Katsuhiro INOUE  Kohji YOSHINAGA  Akira TSUKAMOTO  Kazuo SAITOH  Keiji TSUKADA  Akihiko KANDORI  Yoshinori SUGIURA  Shigenori HAMAOKA  Hiroyuki MORITA  Hiroyuki KUMA  Naotaka HAMASAKI  

     
    INVITED PAPER

      Vol:
    E88-C No:2
      Page(s):
    158-167

    Magnetic immunoassays utilizing magnetic marker and high Tc superconducting quantum interference device (SQUID) have been performed. In this magnetic method, binding-reaction between an antigen and its antibody is detected by measuring the magnetic field from the magnetic marker. First, we discuss the magnetic property of the marker, and show that Fe3O4 particles with diameter of 25 nm can be used for remanence measurement. We also show a design of the SQUID for sensitive detection of the magnetic signal from the marker. Next, we developed a measurement system utilizing the SQUID and a reaction chamber with very low magnetic contamination. Finally, we conducted an experiment on the detection of the biological materials called IL8 and IgE. At present, a few atto-mol of IL8 and IgE has been detected, which shows the high sensitivity of the present method.

301-320hit(575hit)