In this research, the performance degradation of the digital electronic equipment under electromagnetic (EM) disturbance was studied in order to investigate the interference of intra-equipment. To develop the evaluation method of the performance degradation, some communication indexes were measured under EM disturbance. From some experimental results, it is known that the performance degradation of the electronic equipment was estimated by the degradation of "through-put," one of the communication performance indexes. For further investigation of the interference of intra-equipment, the near EM field from a PCB of the electronic equipment and its performance degradation under EM disturbance were measured and compared. From the measured results, the relationship between near field measurement and performance degradation could be obtained in some extent. These facts enable us that the weak area under the EM disturbance application on PCB can be foreseen by measuring the near field emission from the equipment and vise versa.

The peak SAR values of two-element array antennas for mobile handsets in the vicinity of a spherical phantom of a human head are evaluated numerically as a function of the distance between the array antenna and the head phantom when the two elements of a two-element array antenna are either co-phase voltage-fed or reverse-phase voltage-fed. It is found that relation between the worst case of the SAR and the phase difference of array elements strongly depends on the distance. When part of the head phantom is located in the reactive near-field region of the array antenna, although the co-phase feed SAR value is slightly smaller than the reverse-phase feed SAR value, the SAR value is practically independent of the phase difference, but when the head is completely outside the reactive near-field region, the co-phase feed SAR value is larger than the reverse-phase feed SAR value.

This paper proposes a novel signal estimation method that uses a tensor product expansion. When a bivariable function, which is expressed by two-dimensional matrix, is subjected to conventional tensor product expansion, two single variable functions are calculated by minimizing the mean square error between the input vector and its outer product. A tensor product expansion is useful for feature extraction and signal compression, however, it is difficult to separate global noise from other signals. This paper shows that global noise, which is observed in almost all input signals, can be estimated by using a tensor product expansion where absolute error is used as the error function.

The electromagnetic disturbance that leaks from ICT (information and communications technology) equipment might contain important information. Our measurements show that the information hidden inside of the electromagnetic disturbance can be monitored. First, we measured the level of the electromagnetic disturbance that leaks from laser printers and collected the waveform in the time domain. Then, we reconstructed the printed image from the data. As a result of our measurements, we found that at points 200 cm away or beyond it is difficult to reconstruct the printed image, and therefore the threat to electromagnetic security is not significant.

In this paper, the authors propose a circularly polarized printed antenna combining a slot array antenna and a patch antenna, with dual-band operation. The proposed antenna has good isolation performance, is compact, and has simple configuration. This antenna is composed of two parts, a patch antenna (for Rx) on the top, and a slot array antenna (for Tx) on the bottom, respectively. The element layout is such that the lower radiation element is not hidden by the upper one for wide observation angle. Hence, both radiation elements can naturally radiate the targeted polarization. Both slot array and patch antenna are fed by electromagnetically coupled microstrip line feed. With such a configuration, it is possible to efficiently obtain good isolation characteristics for both frequency bands. Furthermore, this antenna can be easily composed and it is not necessary to use any feeding pin or via hole. The target of this antenna is mobile communications applications such as mobile satellite communications, base-station of wireless LAN, etc. Here, the design techniques are discussed and the numerical and experimental analyses are presented.

A major step in the numerical solution of electromagnetic scattering problems involves the computation of the convolution based reaction integrals. In this paper a procedure based on the analytical Fourier transform is introduced which allows us to calculate the convolution-based reaction integrals in the spectral domain without evaluating any convolution products directly. A numerical evaluation of the computational cost is presented to show the efficiency of the method when handling electrically large problems.

A novel procedure for an efficient and rigorous solution of electromagnetic scattering problems is presented. It is based on the use of universal bases that are obtained by applying the SVD procedure to PO-derived basis functions. These bases, constructed by totally bypassing any matrix-type approach, can be used for all angles of incidence and their use leads to a matrix with relatively small dimensions. The method enables us to solve 2D scattering problems in a computationally efficient and numerically rigorous manner.

An iterative reconstruction algorithm of accelerating the estimation of the complex relative permittivity of a cylindrical dielectric object based on the multigrid optimization method (MGOM) is presented. A cost functional is defined by the norm of a difference between the scattered electric fields measured and calculated for an estimated contrast function, which is expressed as a function of the complex relative permittivity of the object. Then the electromagnetic inverse scattering problem can be treated as an optimization problem where the contrast function is determined by minimizing the cost functional. We apply the conjugate gradient method (CGM) and the frequency-hopping technique (FHT) to the minimization of the cost functional, and also employ the multigrid method (MGM) with a V-cycle to accelerate the rate of convergence for getting the reconstructed profile. The reconstruction scheme is called the multigrid optimization method. Computer simulations are performed for lossy and inhomogeneous dielectric circular cylinders by using single-frequency or multifrequency scattering data. The numerical results demonstrate that the rate of convergence of the proposed metod is much faster than that of the conventional CGM for both noise-free and noisy cases.

To make the best use of the known characteristics of the alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method such as unconditional stability and modeling accuracy, an efficient time domain solution with variable time-step size is proposed. Numerical results show that a time-step size for a given mesh size can be increased preserving a desired numerical accuracy over frequencies of interest.

An optically scanning electromagnetic field probe system consisting of an electro-optic or magneto-optic crystal and a galvano scanner is proposed for high-speed electromagnetic field distribution measurements. We used this technique to measure electromagnetic field distributions near printed circuit boards or ICs to address electromagnetic compatibility problems or in designing electronic devices. With our scanning system, we can measure the electric field intensities of about 40,000 points with an area of 4040 mm in about 3 minutes (4 ms per point) up to 2.7 GHz. We measured the electric near-field distribution above a five-split transmission line using a cadmium telluride (CdTe) electro-optic crystal. The measurement results showed that the spatial resolution of the system was less than 400 µm in the case of a common current with a crystal thickness of 1 mm. The electric near-field distribution above a microstrip line filter was measured using LiNbO3 electro-optic crystal. Changes in the distribution according to the frequency were observed. The experimental results obtained using this system were compared with simulation results obtained using a finite-difference time-domain method. The overall results indicated that the measurement system is capable of accurately measuring electric near-fields. We also discuss the invasiveness of the measurement system, due to the electro-optic crystals, in terms of both the experimental and simulated results.

Frequency-modulated clock signals are widely used in personal computers to reduce the amplitude of the clock harmonic noise, as measured using an electromagnetic interference (EMI) test receiver. However, the power of the clock harmonics is not decreased with this technique called spread spectrum clocking (SSC). Hence, the impact of the harmonics of a frequency-modulated clock on the bit error rate (BER) and packet error rate (PER) of a Bluetooth system is theoretically analyzed. In addition, theoretical analysis covers the effectiveness of a frequency hopping spread spectrum (FH-SS) scheme and forward error correction (FEC) in mitigating the degradation in the BER and PER caused by clock harmonic interference. The results indicate that the BER and PER strongly depend on the modulating frequency and maximum frequency deviation of the clock harmonic. They also indicate that radiated clock harmonics may considerably degrade the BER and PER when a Bluetooth receiver is very close to a personal computer. Frequency modulating the clock harmonics slightly reduces the BER while it negligibly reduces the PER.

A rigorous and simple method is proposed for analyzing guided modes of metallic electromagnetic crystal waveguides. The method is a combination of generalized reflection and transmission matrices and the mode-matching technique. Fast convergence, low computer cost, and high calculating precision are main advantages of the proposed method. This method can easily avoid the relative convergence phenomena than a classical mode-matching method, and the proposed formulation is very suitable to analyzing multilayered problems with very low computer cost. The existence of H-polarized modes in metallic electromagnetic crystal waveguides has been verified.

This letter presents mutual coupling reduction in an E-plane arranged microstrip patch array fed by a triplate waveguide. Five mushroom-like electromagnetic band-gap (EBG) elements arranged in one column are embedded both between two radiating patches and between the feeding lines for suppression of the surface wave and the parallel plate mode, respectively. Validity of the proposed EBG elements is confirmed by the measurement.

Electromagnetic crystals formed by vertical full posts stacked in a rectangular waveguide are analyzed using the image theory and the lattice sums technique. It is shown that the frequency response of the crystals consisting of circular posts can be obtained by a simpler matrix calculus based on the one-dimensional lattice sums, the T-matrix of a circular cylinder in free space, and the generalized reflection and transmission matrices.

A new type of permanent magnet actuator driven by electromagnetic repulsive force in breaking course and electromagnetic attraction force during closing course is presented in this paper, and the static and dynamic characteristics for contactor with this new type actuator are mainly focused on by simulation and experiment simultaneously. Firstly, the static electromagnetic attraction force in closing course and electromagnetic repulsive force in breaking course are studied by FEM simulation and experiment. Secondly, by coupling of the electrical and mechanical differential equations, the dynamic electromagnetic attraction force in closing course and dynamic electromagnetic repulsive force in breaking course are obtained respectively. Thirdly, by constructing the mechanical model of contact system and permanent magnet actuator, the displacements of moving contact and moving core while both contactors' closing and breaking are obtained by simulation and experimental study. It is indicated that simulation results coincide well with that of experiment.

At present, during the design of sealed electromagnetic relay, the tolerances of design parameters are given with experience. The designer can't provide quantificational reliability index, and the blindness of tolerance distribution also causes unnecessary increase of machining cost. According to the study of electromagnetic force and spring force characteristics of a certain sealed electromagnetic relay with polarized magnetic system, this paper analyzed the influence of main design parameters' tolerances to the tolerance bands of electromagnetic force and spring force characteristics and achieved the strong correlative factors (viz. design parameters) that have obvious effect on tolerance bands of electromagnetic force and spring force characteristics. Then based on the calculation of reliability, the tolerance distribution method of key design parameters was given. This method not only can make the designed product satisfy requirement of reliability, but also reduce the machining cost.

Vibration characteristic of electromagnetic relay (EMR), including modal and frequency response are important for increasing operational reliability in mechanical environment. The switching contact system, as function execution component of EMR, is the important parts in this product. This paper presents a dynamic model of contact system by introducing Hertz contact theory, and discusses weakly nonlinear oscillation character. Quasilinear simulation analysis using by finite element analyzing software-NASTRAN is investigated. The factors affecting contact vibration characteristic are determined. Finally, theory analysis and simulation results are verified by the vibration test. The model starts from a typical contact system of EMR, but the approach can be applied to other switching electro-mechanical devices.

To provide basic considerations for the realization of methods for predicting the electromagnetic (EM) radiation from a printed circuit board (PCB) with plural signal traces driven in the even-mode, the characteristics of the EM radiation resulting from two signal traces on a PCB are investigated experimentally and by numerical modeling. First, the frequency responses of common-mode (CM) current and far-electric field as electromagnetic interference (EMI) are discussed. As the two traces are moved closer to the PCB edge, CM current and far-electric field increase. The frequency responses in the two signal trace case can be identified using insights gained from the single trace case. Second, to understand the details of the increase in CM current, the distribution of the current density on the ground plane is calculated and discussed. Although crosstalk ensues, the rule for PCB design is to keep two high-speed traces on the interior of the PCB whenever possible, from the point of view of EM radiation. Finally, an empirical formula to quantify the relationship between the positions of two traces and CM current is provided and discussed by comparing four different models. Results calculated with the empirical formula and finite-difference time-domain (FDTD) modeling are in good agreement, which indicates the empirical formula may be useful for developing EMI design guidelines.

A microstrip phase shifter design that uses a reconfigurable metal pattern on the EBG ground plate is introduced. The EBG ground plate metal pattern contains a linear array of thin slots with switching devices loaded at the center. This design can vary the phase constant with minimum mismatch loss over a large frequency bandwidth. Several test ground plates without actual switching devices were used to verify the design concept.

This paper describes a two-dimensional clustering scheme-based analysis of audible noises induced at telephone terminals. To analyze EMI sources that cause telephone-audible noise, we use a self-organizing map, which provides a way to map high-dimensional data onto a two-dimensional domain. Also, in order to discriminate EMI sources without using particular resonance frequencies that have peaks in the frequency domain, we use the energy spectra of telephone-audible noises as input for training the self-organizing map. In applying this method in actual environments, we measured ten kinds of telephone-audible noises (due to Radio waves and cross-talk noises, etc.) and then derived their energy spectra for eight frequency bands: 1-250 Hz, 250-500 Hz, 500-1 kHz, 1 k-1.5 kHz, 1.5 k-2 kHz, 2 k-3 kHz, 3 k-4 kHz, and over 4 kHz. We visually confirmed that the measured telephone-audible noise data could be projected onto the map in accordance with their properties, resulting in a combined depiction of the composition of derived energy spectra in the frequency bands. The proposed method can deal with multi-dimensional parameters, projecting its results onto a two-dimensional space in which the projected data positions give us an effective depiction of EMI sources that cause disturbances at telephone terminals.