Shinji Tanabe

3D-FEM analysis for shielding effects of a metallic enclosure with apertures

The leakage of electromagnetic (EM) waves from a metallic enclosure with apertures, from a metallic mesh and from a metallic shield thinner than the skin depth are numerically analyzed using a three dimensional finite element method (3D-FEM). The calculated results were compared with measured results using a simple shape model enclosure with a generator inside. The phenomena predicted by the numerical analysis agree with the measurement results.

FEM analysis of thin-film inductors used in GHz frequency bands

Three dimensional finite element method (3D-FEM) simulations have been used to study the possibility of magnetic film utilization to make GHz frequency band inductors. A simple structure of a flat magnetic film above a spiral coil gained about 65% inductance increase. Granular type soft magnetic films showed the best results.

Electromagnetic field distribution inside an automobile vehicle

Electromagnetic radiation phenomena due to electronic equipment inside an automobile have been analyzed from both numerical and experimental viewpoints. The numerical procedure is carried out using a hybrid method of a finite difference time domain (FDTD) and a transmission line technique (TL technique). This combined procedure is suitable for solving an automobile with long wires connected to an electric control in it. Numerical results were compared with experimental measurements with a real automobile, showing in a good agreement between them. Finally an FM radio antenna position that minimizes noise intensity caused by electronic control units was determined by the hybrid method.

Reduction of crosstalk noise between interconnect lines in CMOS RF integrated circuits

We have numerically investigated crosstalk noise between interconnect lines in CMOS RF integrated circuits. Immersed microstrip line (IMSL) and immersed coplanar waveguide (ICPW) over Si substrate were analyzed to make clear shielding effect of grounded planes to reduce crosstalk noise between parallel interconnect lines. It was shown that the crosstalk between the interconnect lines were extensively reduced by the use of IMSLs or ICPWs, compared with simple lines. However, in layout designs using ICPWs, we need consideration about the transmission loss due to the electromagnetic coupling with the lossy Si substrate. On the other hand, for IMSL configurations, the transmission loss due to the Si substrate is small, because the ground plane shields the signal line from the electromagnetic coupling with the Si substrate.

3D-FEM analysis of electromagnetic emission from PCB

The emission of electromagnetic (EM) noise from printed circuit boards (PCBs) is analyzed using a three dimensional finite element method (3D-FEM). The emission of EM noise depends on the transmission line structure and ground structure including the connection between the system ground (SG) and frame ground (FG). We applied the 3D-FEM analysis to the design of a thin film transistor liquid crystal displays (TFT-LCD) PCB. The calculation results were confirmed by experiments using model transmission lines. The 360 MHz noise emission from a strip line structure is about 1/10 of that from a microstrip line structure for a particular specification. Plural FGs generate loop currents and increase the noise emission. The distance between the noise source and FG is an important factor in deciding the noise emission.

Near and far fields analysis from flat cables

The electromagnetic radiation from flat cables (flexible printed circuit:FPC) which have different structures are analyzed using a three dimensional finite element method (3D-FEM). The electric fields at 3 m from the FPC were calculated by an integration method using the calculated E and H values inside of the FEM region and Greens function. The calculated radiation from a microstrip structure FPC is smaller than that from a single layer FPC by about 17 dB in near field, 25 dB at 3 m from the FPC. The results were compared with E fields measured by antenna at 3 m from the FPC. The measured difference between the microstrip FPC and the single layer FPC is 11.5 dB. Adopting a microstrip structure FPC is effective in drastically reducing the EMI noise from the cable.

EMI noise analysis of plasma display panels

The radiation of electromagnetic (EM) noise from a plasma display panel (PDP) is analyzed using a three dimensional finite element method (3D-FEM) and measurements. The EM noise is not only the harmonic noise from the digital circuits, but also the broad band noise from the panel itself. The EM noise amplitude depends on the displayed patterns of the panel. From the measurements of the noise from different displayed patterns and the timing of the noise emission, we found that one of the main reasons for the radiation from the panel is the displacement currents between the electrodes of the panel. This phenomenon was confirmed by the computation using a 3D-FEM. The EM noise from the panel can be decreased by optimizing waveforms of driving pulses and the grounding method of the panel electrodes.

Influence of remanence magnetization on asymmetry of reproducing signals in 4MB FDD heads

A head combined with a read/write (R/W) gap and a pre-erase gap has been adopted for 4 MB flexible disk drives. The cross-talk coupling from the erase head to the R/W head can be suppressed by decreasing the permeability of the head material. However, decreasing the permeability of the erase head material increases the coercive force. Therefore, a remanence magnetization is induced in the erase head core during the reproducing process, which increases the asymmetry of reproduced waveforms. In order to decrease this asymmetry, a head with back gaps is developed. By controlling the back gap length to minimize the cross-talk, it is possible to realize both low asymmetry and low cross-talk simultaneously for 4 MB FDD heads.

Design method of a metallic enclosure considering EMI using a 3D-FEM

The leakage of electromagnetic radiation from a metallic enclosure with apertures is numerically analyzed by solving Maxwells equations directly using a three dimensional finite element method (3D-FEM). This method applied for designing a metallic enclosure for an asynchronous transfer mode digital service unit (ATM-DSU) to decrease EMI in the range of 30 MHz to 1 GHz.

3D-FEM analysis for microwave reflection and absorption on/in dielectric materials with conductivity

The finite element method (FEM) has many frequency sinusoidal waves. The authors tried to apply FEM to the analysis of microwave (28 GHz) reflection and adsorption on/in concrete material (/spl epsiv//sub r/=5, /spl sigma/=0.19 [S/m]). The reflection rate and adsorption rate for plane waves injected perpendicularly to the concrete surface agree with the values obtained by analytical methods. The method was applied to the problem of reflection and adsorption for a mixture material. The electric current concentration around a water particle inside concrete was analyzed.