Kouta Matsumoto

Wave Absorber Based on Rubber Sheet with Circular Lattice for Installing between ETC Lanes

A wave absorber based on rubber sheet with circular lattice is proposed for improving ETC environment, and characteristics of reflection loss and shielding effect are analyzed and measured. As a result, various characteristics of absorber can be confirmed quantitatively by changing the hole diameter and the pitch interval between holes. Furthermore, it is clarified that reflection loss of -27 dB and shielding effect of -18.5 dB is obtained at 5.8 GHz when the hole diameter is 10.0mm and the pitch interval is 16.0 mm (the ratio of hole is 35.4%). Therefore, the wave absorber with circular lattice that satisfies various characteristics required for the improvement of ETC environment can be obtained analytically and experimentally

Magnetic Field and Dosimetric Study at Intermediate Frequency Range Using the Coil Source Model

In this paper, the magnetic field properties and the dosimetry at intermediate frequency (21 kHz) for an induction heater are investigated with the coil model, which is prescribed as substitute source model in the European standard EN50366 (CENELEC). The accuracy of the magnetic field vectors and the values of the induced current density, which are achieved with the coil model, are compared with the results of a realistic model of the induction heater obtained from the equivalent source model. It is shown that the coil model coincides well for the magnitude of the magnetic field strength around the induction heater. On the other hand, the dominant field vector of the coil model differs significantly from the real induction heater, which leads to induced current densities in the body model which are three time larger. Owing to these results, the applicability of the coil model prescribed in the EN50366 is confirmed for the induction heater.

Wave Absorber Formed by Arranging Cylindrical Bars at Intervals for Installing between ETC Lanes

The wave absorber which is formed by arranging cylindrical bars periodically composed of magnetic loss material and metallic bars is proposed for improving ETC environment, and characteristics of reflection loss and shielding effect are analyzed and measured. As a result, the change of various characteristics can be confirmed quantitatively by changing the thickness of magnetic loss material covering around a metallic bar and the pitch interval between bars. Furthermore, it is clarified that reflection loss of -9 dB and shielding effect of -25 dB are obtained at 5.8 GHz when the covering thickness of material is 1.5 mm and the pitch interval is 16.0 mm. Therefore, the wave absorber formed by arranging cylindrical bars that satisfies various characteristics required for the improvement of ETC environment can be realized.

An efficient analysis on door structure of a microwave oven using combined waves of higher order modes

This paper describes propagation modes of leakage waves irradiated from a microwave oven examined by using finite difference time domain(FDTD) method. In this study, the amplitude coefficient in each mode of leakage waves is calculated under the use of the amplitude level of the elctric field about these unwanted waves, and the percentage of each mode is also calculated. Furthermore, shielding effectiveness(SE) of choke structure for suppressing the leakage waves is calculated using combined waves composed of the higher order modes as each percentages. As a result, the percentage of each mode included in the leakage waves in examined quantitatively. The approximation analysis of the SE of the choke structure can also be carried out. Therefore, efficient method for analyzing the door structure of the oven has been established without the use of the memory for the calculation.

Wave absorber based on reinforced plastic with periodic lattice for improving ETC environment

A wave absorber based on reinforced plastic including glass fiber with periodic lattice is proposed, the absorption and the shielding effect are examined at 5.8 GHz for ETC. As a result, the absorption of 10 dB or more can be obtained at the incident angle ranging from 5 to 55 degrees for circularly polarized wave. Furthermore, the shielding effect of 20 dB or more is also obtained. Therefore, realization of the wave absorber with periodic lattice for ETC is clarified.

Wave Absorber with Fine Weatherability for Improving ETC Environment

Wave absorber of rubber sheet containing natural rubber and EPDM is designed, fabricated and measured for improving ETC environment. As a result, proposed absorption material has fine weatherability and wave absorption satisfied with ETC standard can be realized theoretically before and after the weatherability test if the thickness of absorber is fabricated at the ranging from 2.26mm to 2.52mm. Moreover, absorber sheet sample based on theoretical values is fabricated and are measured. As a result, 20dB or more is also confirmed at the incident angle ranging from 5 to 55 degrees experimentally. Therefore, the wave absorber with fine weatherability being satisfied with ETC standard can be realized.

Wave Absorber by Using Cylindrical Bars with Magnetic Loss Covers Arranged Metallic Mesh for Improving ETC Environment

The wave absorber composed of cylindrical bars arranged periodically and metallic mesh for improving visibility is proposed for ETC, and characteristics of reflectivity and shielding effect are evaluated analytically and experimentally. As a result, reflectivity of -10dB and shielding effect of -25dB are obtained for circularly polarized wave when the gap between cylindrical bars is 30mm. Therefore, realization of proposed wave absorber for installing between ETC lanes can be clarified.

Wave absorber with circular lattice using metal mesh for improving ETC environment

A wave absorber based on rubber sheet with circular lattice using metal mesh is proposed for improving ETC environment, and characteristics of the reflectivity and the shielding effect are evaluated analytically and experimentally. As a result, it is confirmed that the reflectivity of -13dB at the incident angle ranging from 5 to 45 degrees and the shielding effect of -25dB at the incident angle ranging from 0 to 30 degrees are obtained for circularly polarized wave used in ETC system. Therefore, realization of proposed wave absorber can be clarified.

Wave Absorber by Using Cylindrical Bars with Magnetic Loss Covers Arranged Metallic Mesh for Installing between ETC Lanes

The wave absorber composed of cylindrical bars arranged periodically and metallic mesh for improving visibility is proposed for ETC, and characteristics of reflectivity and shielding effect are evaluated analytically and experimentally. As a result, reflectivity of -10 dB and shielding effect of -25 dB are obtained for circularly polarized wave when the gap between cylindrical bars is 30 mm. Therefore, realization of proposed wave absorber for installing between ETC lanes can be clarified.

Shield design about circumference of choke structure used for microwave oven by parallel FDTD

An analytical model about circumference of choke structure used for improving shielding effectiveness (SE) of mass-produced microwave oven, which is composed by parallel FDTD method and thereby SE at four sides of the door is rigorously calculated. As a result, it has confirmed quantitatively that SE of 30 dB or more has been obtained in circumference of the choke structure.