Electromagnetic wave scattering in two open-ended coaxial cables with flanges is presented for adiabatic transmission line applications. Field distributions in the cables are obtained by employing the mode-matching method. A set of simultaneous equations is solved to investigate the transmission and reflection coefficients.

Application of transverse magnetic field (TMF) is one of the most important ways to improve electric life and breaking capacity of DC relays. For better understanding of dependence of arc durations on transverse magnetic field, a series of experiments were conducted under an external transverse magnetic field with 12 pairs of AgSnO2 contacts in a DC 28 V 60 A/30 A/5 A circuit, respectively. By using permanent magnets, the transverse magnetic field was obtained and the magnetic flux density at the gap center was varied from 13 to 94 mT. The results show that breaking arc duration is decreased monotonically with increases in the magnetic flux density, but making arc duration isn't decreased monotonically with increases in the magnetic flux density. In addition, both the magnetic flux density and the breaking arc duration have threshold values Bl and Tbmin, respectively, which means the breaking arc duration is almost stable with the value Tbmin even if the magnetic flux density is higher than Bl.

This paper focuses on the latest research of switching arc both in vacuum and SF6 substitutes in our group. The crucial characteristics of vacuum arc are illustrated, including the motion and distribution of single cathode spot and multiple cathode spots, the influence of axial magnetic field on arc plasma characteristics, the influence of composite magnetic field on cathode jets, and the study of anode activities. Meanwhile, the arc characteristics in SF6 and its substitutes (Ar, CO2 and N2) at different pressures and gap distances are investigated by experiments and simulation.

Experiments were carried out at several voltages to clarify the influence of the voltage on various characteristics, i.e. arc duration, contact resistance, arc energy, and the change in electrode mass. The voltage was varied from DC100 V to 160 V, the load current was fixed at 5 A constant, and the electromagnetic contactor was operated continuously up to 100,000 times. The experiments were carried out under the three operation modes which are classified by the arc discharge. As a result, the relation between the operation mode and contact resistance was clarified. When only a make arc was generated, the contact resistance was smallest. In addition, the contact resistance was not affected by the source voltage.

Silver electrical contacts are separated at constant speed and break arcs are generated in a DC100 V–450 V/10 A resistive circuit. The transverse magnetic field of a permanent magnet is applied to the break arcs. Dependences of the arc duration, arc dwell time and arc lengthening time on the strength of the magnetic field and supply voltage are investigated. The characteristics of the re-ignition of the break arc are also discussed. Following results are shown. The arc duration D is increased due to the increase of the arc lengthening time tm when the supply voltage E is increased for each magnetic flux density Bx, because the arc dwell time ts is almost constant. The arc duration D is increased due to the increase of both of the arc lengthening time tm and the arc dwell time ts when the magnetic flux density Bx is decreased. The arc lengthening time tended to become long when the re-ignition of the break arc is occurred. The lengthening time tends to become longer when the duration tm1 from the start of the arc lengthening to the start of the re-ignition is increased. Re-ignitions occurred frequently when the magnetic flux density of the transverse magnetic field is increased and the supply voltage is increased.

The circuit switching device by the electrical contact needs the high reliability and long lifetime. The very important factor for the high reliability, long lifetime and electromagnetic noise of the electrical contact is to suppress the duration and electromagnetic noise of arc discharge. Usually, the suppression of arc duration method is applying the external magnetic field. But, this method was not able to suppress the metallic arc duration and increased the voltage fluctuation at arc duration. Therefore, the new method for suppressing the duration and noise for electrical contact is expected. In this paper, a new method for suppressing duration and EM noise of arc discharge by applying housing pressure is proposed. To investigate the availability of proposed method, the measurement and some considerations on arc duration, voltage-fluctuation and current noise up to GHz frequency band generated by breaking contact in the applied pressure relay housing are reported. Firstly, voltage waveform and duration of the arc are measured. The effects of the pressure in the relay housing on the duration of the metallic and gaseous phase arcs are discussed. Secondary, voltage fluctuation, the spectrogram of contact voltage and current noise up to GHz frequency band are discussed. In the results, the proposed method with applying pressure makes shorter both durations of metallic and gaseous phases. The shorter duration of metallic phase is an advantage of the proposed method beyond the applying external magnetic field. As the housing pressure is increase, the voltage fluctuation and current noise becomes smalls. The proposed method can suppress the voltage fluctuation as well as arc duration. Consequently, the proposed method is on of the good solution to suppress the duration and electromagnetic noise of the arc discharge from electrical contact and result of this study indicates the basic considerations necessary to ensure good lifetime and EMC designs for electrical contacts.

Break arcs are generated in a DC48 V and 10 A resistive circuit. The external transverse magnetic field of a permanent magnet is applied to the break arcs. The position and shape of the break arc are investigated. As a result, it is confirmed that the cathode spot region was shifted upward earlier than the anode spot region. This result shows that the cathode spot region is easily driven by the transverse magnetic field than the anode spot region.

In this paper, a new swept-frequency method for the measurement of the complex permittivity and permeability of materials is proposed. The method is based on the S-parameters measurement of a cylindrical material placed inside a rectangular waveguide, where the axis of the cylinder is perpendicular to the narrow waveguide walls. The usage of cylinders in measurement is beneficial because they are easy to fabricate and handle. A novel exact solution of the field scattered by the cylinder is developed. The solution is based on expanding the field in a sum of orthogonal modes in cylindrical coordinates. Excitation coefficients relating the cylindrical scattered field to the waveguide modes are derived, and are used to rigorously formulates the S-parameters. Measurement are performed in the S-band with two dielectric materials (PTFE, nylon), and in the X-band with one magnetic material (ferrite epoxy). The measurement results agree with those from the literature.

This paper presents a possibility of Electromagnetic (EM) analysis against cryptographic modules outside their security boundaries. The mechanism behind the information leakage is explained from the view point of Electromagnetic Compatibility: electric fluctuation released from cryptographic modules can conduct to peripheral circuits based on ground bounce, resulting in radiation. We demonstrate the consequence of the mechanism through experiments where the ISO/IEC standard block cipher AES (Advanced Encryption Standard) is implemented on an FPGA board and EM radiations from power and communication cables are measured. Correlation Electromagnetic Analysis (CEMA) is conducted in order to evaluate the information leakage. The experimental results show that secret keys are revealed even though there are various disturbing factors such as voltage regulators and AC/DC converters between the target module and the measurement points. We also discuss information-suppression techniques as electrical-level countermeasures against such CEMAs.

This paper presents a new type of electromagnetic interference (EMI) measurement system. An EMI Camera LSI (EMcam) with a 124 on-chip 25050 µm2 loop antenna matrix in 65 nm CMOS is developed. EMcam achieves both the 2D electric scanning and 60 µm-level spatial precision. The down-conversion architecture increases the bandwidth of EMcam and enables the measurement of EMI spectrum up to 3.3 GHz. The shared IF-block scheme is proposed to relax both the increase of power and area penalty, which are inherent issues of the matrix measurement. The power and the area are reduced by 74% and 73%, respectively. EMI measurement with the smallest 3212 µm2 antenna to date is also demonstrated.

The cause-and-effect relation between plasmon-resonance absorption and surface wave in a sinusoidal metal grating is investigated. By introducing an equivalent impedance model, similar to an equivalent circuit on an electric circuit, which is an impedance boundary value problem on the fictitious surface over the grating, we estimate the surface wave from the eigen field of the model by using the resonance property of the scattered field. Through numerical examples, we illustrate that the absorption in the grating occurs in the condition of exciting the surface wave along the model, and the real part of the surface impedance is negative on about half part of the fictitious surface in the condition.

In this paper, the author proposes an electromagnetic coupling fed inverted-FL antenna design. The inverted-FL antenna with a self-complementary structure has been reported as a way to achieve a constant impedance of 188 ohms without the need for a matching load, since the axially symmetric self-complementary antenna has constant impedance, even though it has a finite structure. This design has been realized by integrating an inverted-F antenna with a self-complementary structure for achieving a broadband characteristic and an inverted-L element for operation on a frequency lower than the minimum frequency of the antenna. The proposed antenna realizes a broadband characteristic without attaching the matching load and the impedance transformer to match 50 ohms. The impedance transformer necessary for the inverted-FL antenna with a self-complementary structure is removed by using an electromagnetic coupling feed structure. This antenna, which has a volume of 101045 mm3, obtained broadband and multi-band characteristics covering the GSM850/GSM900/DCS/PCS/UMTS2100/UMTS2600 bands and the 2.5 G/3.5 G bands for Mobile-WiMAX in simulation and measurement.

Magnetic particle imaging (MPI), in which the nonlinear interaction between internally administered magnetic nanoparticles (MNPs) and electromagnetic waves irradiated from outside of the body is utilized, has attracted attention for its potential to achieve early diagnosis of diseases such as cancer. In MPI, the local magnetic field distribution is scanned, and the magnetization signal from MNPs within a selected region is detected. However, the signal sensitivity and image resolution are degraded by interference from magnetization signals generated by MNPs outside of the selected region, mainly because of imperfections (limited gradients) in the local magnetic field distribution. Here, we propose new methods based on correlation information between the observed signal and the system function–defined as the interaction between the magnetic field distribution and the magnetizing properties of MNPs. We performed numerical analyses and found that, although the images were somewhat blurred, image artifacts could be significantly reduced and accurate images could be reconstructed without the inverse-matrix operation used in conventional image reconstruction methods.

Axial and transverse magnetic fields are widely used in many kinds of switches to decrease the arc erosion. In this paper, the influence of these two kinds of magnetic fields on the arc phase transition was studied particularly for AgSnO2 contacts breaking a 28 V/25 A circuit. The experiments were carried out under resistive and inductive loads in an atmospheric environment. The relationships between flux densities ranging from 0 to 200 mT and the arc duration were obtained. It was found that the transverse magnetic field was more efficient in balancing the arc phases and decreasing the arc erosion. The results can be used to guide the design of arc extinguishment systems in DC high power relays.

A novel dual-band magnetic loop antenna is proposed using slot-loaded composite right/left-handed (SL-CRLH) structures. Since each radiating element consists of a symmetrically-array of unit-cells, a dual-band magnetic loop source is obtained with unchanged beam patterns. Simulations and measurements show its good radiation performance with monopole-like radiation patterns in both operating bands.

An adaptive and iterative intertrack-interference (ITI) cancelling scheme is described for multi-track signal detection in inter-track asynchronous shingled write magnetic recording. There is write-clock frequency drift in asynchronous recording systems. Read-back signals obtained with a wide read head scanning narrow tracks thus suffer from not only intersymbol interference (ISI) but also time-variant ITI. To efficiently cope with static ISI and time-variant ITI, multi-track soft interference cancellers and two-dimensional partial-response filters are incorporated based on per-survivor processing into each trellis state defined in a one-dimensional/two-dimensional trellis-switching max-log-MAP detector. In addition, the computational complexity can be reduced based on channel interpolation and intermittent TDPR-filter control by allowing small degradation in signal detection. Computer simulation results in media-noise-dominant environments demonstrate that the proposed adaptive and iterative ITI canceller achieves bit error rates close to those obtained in a non-ITI case when the read-head off-track ratio is up to 50% in write-clock frequency difference of 0.02%.

The electric field mill in our underground observation room detected a co-seismic electromagnetic signal in the vertical electrostatic field ca. 8 s after the origin time of the Niigataken Chuetsu-oki Earthquake in 2007, but ca. 30 s before the arrival time of the P-waves.

We introduce a novel method to optimize field decomposition for a mode matching technique. Using our method, expanded mode numbers can be minimized to achieve the desired digits of computational accuracy.

This paper presents the iterative progressive numerical methods (IPNMs) based on the induced dimension reduction (IDR) theorem. The IDR theorem is mainly utilized for the development of new nonstationary linear iterative solvers. On the other hand, the use of the IDR theorem enables to revise the classical linear iterative solvers like the Jacobi, the Gauss-Seidel (GS), the relaxed Jacobi, the successive overrelaxation (SOR), and the symmetric SOR (SSOR) methods. The new IPNMs are based on the revised solvers because the original one is similar to the Jacobi method. In the new IPNMs, namely the IDR-based IPNMs, we repeatedly solve linear systems of equations by using a nonstationary linear iterative solver. An initial guess and a stopping criterion are discussed in order to realize a fast computation. We treat electromagnetic wave scattering from 27 perfectly electric conducting spheres and reports comparatively the performance of the IDR-based IPNMs. However, the IDR-based SOR- and the IDR-based SSOR-type IPNMs are not subject to the above numerical test in this paper because of the problem with an optimal relaxation parameter. The performance evaluation reveals that the IDR-based IPNMs are better than the conventional ones in terms of the net computation time and the application range for the distance between objects. The IDR-based GS-type IPNM is the best among the conventional and the IDR-based IPNMs and converges 5 times faster than a standard computation by way of the boundary element method.

Error analysis of the multilevel fast multipole algorithm is studied for electromagnetic scattering problems. We propose novel error prediction and control methods and verify that the computational error for scattering problems with over one million unknowns can be precisely controlled under desired digits of accuracy. Optimum selection of truncation numbers to minimize computational error also will be discussed.