This paper describes a new approach to analyze nonlinear characteristics of propagating waves in a ferrite material. As to the formulation of the wave in a ferrite medium, the analysis in this paper is not taken under the assumption of a sinusoidal steady state using Polder tensor permeability, but taken by directly differentiating the gyromagnetic equation in time domain without any linear approximations. Then it is combined with Maxwell equation in FDTD procedure. As a result, intensity-dependent nonlinear responses of the propagating wave are confirmed, and the nonlinearity is seen in only the right-hand polarization wave. It is also found that an effect of the damping term in the equation of the motion of the magnetization has nonlinear characteristics for wave propagation.

We have proposed an algorithm to apply perfectly matched layer (PML) absorbing boundary condition to the noncubic cell time-domain method. The extended method has a merit of flexibility in truncating the computational domain by the use of a curvilinear PML. In this paper we apply a circular PML for computing the scattered fields of a dielectric cylinder or cylindrical shell of arbitrary cross section shape. Numerical results are presented to demonstrate the accuracy of this method.

This paper presents a relationship between the near-field shielding effectiveness (SE) and the far-field SE of an infinite planar shield for dipole fields. The penetration fields through the shield and the near-field SE are deduced analytically from an explicit integral expression based on certain assumptions. They further give us approximate formulas for the near-field SE. The near-field SE depends on not only wavelength and material used, but also on the distance r from a source to an observation point through the shield, the source type (magnetic dipole or electric dipole) and the orientation (vertical or horizontal to the shield face) in general. The results we obtained are as follows. The near-field SE for magnetic dipole fields vertical to the shield face is the same as that horizontal to the shield face, and their absolute values equal that of the far-field SE multiplied by k0r/3 (k0 is the wave number). The near-field SE for electric dipole fields vertical to the shield face doubles that horizontal to the shield face, and the absolute value of the latter equals that of the far-fields SE divided by k0r. The validity of the assumptions used to obtain the approximate formulas are examined. The range of r (an application range), over which the difference between the approximate value and the true value is under 1 dB, is determined, where the former value is calculated by the approximate formula of the SE and the latter value is etsimated by direct integration of the related integral expression. For instance, an application range of the approximate formula for magnetic dipole fields vertical to the shield face is from larger one of 50δ and 33µrδ to 0. 11λ0, where µr is specific permeability, δ is skin depth of the shielding material used and λ0 is wavelength in the free space.

In the ITS (Intelligent Transport Systems), it is an essential condition (mixed environment) that vehicles that have communication equipment and vehicles that do not have it simultaneously run in the same road. In this paper, a vehicular driving assistant system that is applicable to the mixed environment is proposed. The proposed system uses spread spectrum techniques and consists of several new systems such as a PN code assignment system, new vehicle position systems, and a vehicle map update system. In the proposed system, the wireless broadcast CDMA is used for inter-vehicle communications. This paper also shows preexaminations of the proposed system by using an autonomous traffic flow simulator including inter-vehicle communications. It is shown that the traffic safety can be improved by using inter-vehicle communications.

An efficient finite element-integral equation method is presented for calculating scattered fields from conducting objects. By combining the integral equation solution with the finite element method, this formulation allows a finite element computational domain terminated very closely to the scatterer and thus results in the decrease of the resultant matrix size. Furthermore, we employ a new integral approach to establish the boundary condition on the finite element terminating surface. The expansion of the fields on the integration contour is not related to the fields on the terminating surface, hence we obtain an explicit expression of the boundary condition on the terminating surface. Using this explicit boundary condition with the finite element solution, our method substantially improves the computational efficiency and relaxes the computer memory requirements. Only one matrix inversion is needed through our formulation and the generation and storing of a full matrix is not necessary as compared with the conventional hybrid finite element methods. The validity and accuracy of the formulation are checked by some numerical solutions of scattering from two-dimensional metallic cylinders, which are compared with the results of other methods and/or measured data.

In general, the performance of partial response maximum-likelihood (PRML) system is degraded by nonlinear distortion and high frequency noise in high-density digital magnetic recording. Conventional PRML system for single-track recording improves the performance when high order PRML systems and high rate codes are adopted. But, in general it is difficult to realize LSI circuits for high order PRML system and high rate code. In this paper, a trellis coded class four partial response maximum-likelihood (TC-PR4ML) system for high density two-track digital magnetic recording is proposed. Our two-track recording method can increase the coding rate over 1, which contributes to a decrease in both degradation effects from partial erasure, one of nonlinear distortions, and high frequency noise in high density recording. The error rate performance of the proposed system is obtained by computer simulation taking account of the partial erasure and it is compared with that of a conventional NRZ coded class four partial response maximum-likelihood (NRZ-PR4ML) system. The results show that the proposed system is hardly affected by partial erasure and keeps good performance in high density recording.

A technique for generating the standard EM fields with arbitrary wave impedance at the center of a TEM cell is proposed in this letter. We can realize the experimental system and obtain the measured results to agree well with the calculated results. This technique is useful for the EMS test and the calibration of EM probe because the wave impedance can be easily adjusted only with step attenuator.

Contact recording systems have been studied for future magnetic recording disks with a high recording density. Tribological key technologies for ultra-low spacing and high wear performance are required for the contact systems. Particularly, a liquid lubrication system plays an important roll for reducing a mechanical spacing and improving wear performances. However, a lubrication design concept for contact recording systems is not established. In this study, molecular design of lubricants for contact systems will be discussed from a viewpoint of bouncing and wear behaviors. As a result, a minimum bouncing height of 3 nm and a high wear performance were obtained for ion-etched contact sliders by the optimization of design parameters, i. e. pad design and lubricant material.

The tape deformation due to such particles as wear debris and dust in the head/tape contact region is one of the main causes of the signal quality deterioration in magnetic tape devices. Thus it is significant to make clear the tape deformation due to a particle for realizing higher recording densities. This paper investigates the tape deformation profile generated by a particle through an interferometric experiment and a simulation using a point loaded tape model. A rather good agreement between them is obtained, thereby the simulation is verified appropriate to estimate the tape deformation due to a particle. This paper also describes the relationship between the spacing loss and the particle height, considering the tape deformation profile obtained from the simulation. In addition, the influence of the particle height on the width of the tape deformed area is estimated, which can make a basis of the design of error correction code.

It is shown from the Hilberts theory that if the real function Π(θ) has no zeros over the interval [0, 2π], it can be factorized into a product of the factor π+(θ) and its complex conjugate π-(θ)(=). This factorization is tested to decompose a real far-zone field pattern having zeros. To this end, the factorized factors are described in terms of bicomplex mathematics. In our bicomplex mathematics, the temporal imaginary unit "j" is newly defined to distinguish from the spatial imaginary unit i, both of which satisfy i2=-1 and j2=-1.

The H-polarized diffraction by a wedge consisting of perfect conductor and lossless dielectric is investigated by employing the dual integral equations. Its physical optics diffraction coefficients are expressed in a finite series of cotangent functions weighted by the Fresnel reflection coefficients. A correction rule is extracted from the difference between the diffraction coefficients of the physical optics field and those of the exact solution to a perfectly conducting wedge. The angular period of the cotangent functions is changed to satisfy the edge condition at the tip of the wedge, and the poles of the cotangent functions are relocated to cancel out the incident field in the artificially complementary region. Numerical results assure that the presented correction is highly effective for reducing the error posed in the physical optics solution.

Scattering data from radar targets are analyzed in the time-frequency domain by using wavelet transform, and the scattering mechanisms are investigated. The wavelet transform used here is a powerful tool for the analysis of scattering data, because it can provide better insights into scattering mechanisms that are not immediately apparent in either the time or frequency domain. First, two types of wavelet transforms that are applied to the time domain data and to the frequency domain data are defined, and the multi-resolution characteristics of them are discussed. Next, the scattering data from a conducting cylinder, two parallel conducting cylinders, a parallel-plate waveguide cavity, and a rectangular cavity in the underground are analyzed by using these wavelet transforms to reveal the scattering mechanisms. In the resulting time-frequency displays, the scattering mechanisms including specular reflection, creeping wave, resonance, and dispersion are clearly observed and identified.

This paper presents a method of analyzing the electromagnetic field inside an equipment housing. The electromagnetic field is assumed to be coming from outside and coupled into the housing through an aperture on the housing surface. The analysis is based on the transmission-line modeling method. Results of the analysis show a good agreement with the results of measurement. Also, it is found that the coupling through the aperture shows peaks at some frequencies that depend almost only on the structure of the housing and aperture and, therefore, can be estimated at the time of equipment design.

Nonlinear phenomena in perpendicular magnetic recording employing a single-pole head and a double-layered medium were investigated. First, measurement of linear superposition in the time domain indicated than the amount of nonlinear transition shift (NLTS) was less than 10 nm. It was concluded that the nonlinearity was caused by transition shift, not by waveform distortion. By interpreting the results, we proved that the NLTS was strongly related with head field gradient and interference field from recorded magnetization. Dependence on head parameter was examined by experiments. Based on the results, a single-pole head with which transition shift can be reduced was proposed. Pseudo-random sequence analysis revealed that NLTS was several percent even at 318 kFRPI, or at a bit interval of 80 nm, which agreed with the result of measurement of linear superposition in the time domain analysis. Experiments showed that NLTS increases the shortest bit length, in contrast with the case of longitudinal recording.

A punctured convolutional coded PR4ML system for digital magnetic recording, which applies a punctured coding method to the convolutional code and records the punctured code sequences on two tracks, is proposed. In this study, the bit error rate performance of the proposed system is obtained by computer simulation taking account of partial erasure, which is one of the nonlinear distortions at high densities, and it is compared with those of a conventional 8/9 coded PR4ML system and an I-NRZI coded PR4ML system. The results show that the proposed system is hardly affected by partial erasure and exhibits good performance in high-density recording. A bit error rate of 10-4 can be achieved with SNR's of approximately 13.2 dB and 9.1 dB less than those of the conventional 8/9 coded and I-NRZI coded PR4ML systems, respectively, at a normalized linear density of 3.

We have constructed a new concept device with combination of ferroelectric and ferromagnetic materials by a laser ablation technique. An ideal hetero-epitaxy can be obtained owing to the similar crystal structure of perovskite type ferroelectric Pb (Zr, Ti) O3; (so called PZT) and ferromagnetic (La, Sr) MnO3. The ferromagnetic (La, Sr) MnO3 compounds are well known for their colossal magnetoresistance (CMR) properties. The CMR effect is strongly affected by the lattice stress. The PZT, on the other hand, is famous for its large piezoelectrics. We can introduce the lattice stress easily by applying voltage for the piezoelectric compounds. In the heterostructured ferromagnetic/ferroelectric devices, there are remarkable interesting phenomena. Electric properties of the ferromagnetic material can be controlled by piezoelectric effect via distortion of crystal structure.

Scattering of a plane electromagnetic wave by a conducting wedge will be discussed. The former solution can not be applicable to all the transition regions when its parameter is constant. This study shows a new solution which consists of only one expression applicable to the shadow region, the illuminated region and the transition regions, and which has no parameter.

Our compact switching converter using a thin-film microtransformer mono-lithically integrated with rectifier diodes represents the first step in developing a monolithic micro-switching converter that can be integrated with semiconductor devices and magnetic components. This converter is a single-ended forward converter with resonant reset and operates successfully at 15 MHz. The maximum output power is 0.5 W.

A detailed investigation of the electromagnetic field distributions inside waveguide circuits is useful for physical understanding, studies of electromagnetic coupling effects for EMC and EMI and for optimization of waveguide circuit designs. In this paper, we describe how to calculate and measure the two-dimensional electromagnetic field distributions inside waveguide-type planar circuits, making use of an analogy between H-plane waveguide- and trough-type surface-wave planar circuits. The measurement results are in good agreement with the results of the numerical analysis based on the normal mode expansion method.

A simple method based on the pattern integration method for measuring the power absorption by human model in the vicinity of antennas is proposed. Good agreement between the measured and the numerical results is obtained conforming the validity of the present measurement method. The equipment is useful in the EMC measurement and research of the antennas for the portable telephone.