Development of Electromagnetic Wave Absorbers Having the Ultra Wide Bandwidth Absorbing Center Frequency
| Project/Area Number |
14550309
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | DOSHISHA UNIVERSITY |
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Principal Investigator |
YOSHIKADO Shinzo Doshisha University, Faculty of Engineering, Professor, 工学部, 教授 (00158403)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2002: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Ultra wideband / SiO_2 / Ni-Zn-ferrite / composite electromagnetic wave absorber / complex permeability / resistive thin film / grain-size dependence / surface coating / 複合体 / スプレー法 / 表面コーティング / 導電率低減 |
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| Research Abstract |
We developed conductor-backed single layered electromagnetic wave absorbers made of ferrite composites (spinel-type Ni-Zn ferrite, SiO_2) having the ultra wide bandwidth absorbing center fFrequency. The density and the hardness are improved by adding B_2O_3, but the conductance value increases with increasing the density. It degrades the absorption characteristics of a metal-backed single layered electromagnetic wave absorber in the high-frequency region. The conductivity was reduced by adding oxides such as CoO, NiO or MnCO_3. The complex permeability, however, decreased for the ferrite composites with added CoO or NiO but did not change for that with added MnCO_3. Composite electromagnetic wave absorbers fabricated by adding B2O_3 and NiO or MnCO_3 operated in the frequency region up to 6 GHz without decreasing both the density and the hardness. The ferrite composite with added B_2O_3 and MnCO_3 had a wide selection range of the absorbing center frequency by simply changing the thick
… More
ness while maintaining the absorption characteristics.
Electromagnetic wave absorbers coated with ITO thin film with the required center absorbing frequency can be made by choosing the suitable thicknesses of both the film and the ferrite composite without changing the composition of the absorber. Absorbing characteristic of electromagnetic wave absorbers added CoO or NiO having required center absorbing frequency below approximately 5GHz can be achieved by coating of ITO thin film with the suitable thicknesses or resistivity without changing the composition.
The absorption characteristics of ferrite composites using fine powders of SiO_2 with the average grain size of approximately 30 nm, 12 nm or 7 nm were improved compared with those of ferrite composites using SiO_2 powders of the average grain size of approximately 29 mm in the low frequency region below 1 GHz. Furthermore, grain size dependence of ferrite composites of fine powders of Ni-Zn ferrite (20 mol%) and SiO_2 (80 mol%) with the normal size such as 29 mm was investigated by the simulation using the model. Result of simulation shows that electromagnetic waves above 90 % in the wide frequency region similar so Ni-Zn ferrite is absorbed in the low frequency region below 1 GHz and is absorbed in the high frequency region above 1 GHz by changing the thicknesses of the absorbers. Less
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Report
(3 results)
Research Products
(22 results)
