Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5490130 | Journal of Magnetism and Magnetic Materials | 2017 | 4 Pages |
Abstract
Feasibility of realizing a noise suppression sheet (NSS) coping with the low SHF band such as the 5 GHz band was investigated, which was composed of soft magnetic metal flakes dispersed in a polymer. For suppressing noises, the higher frequency one of the bimodal frequency dispersion (lower frequency one: Dispersion DII, higher frequency one: Dispersion DIII) seen in the imaginary permeability (μâ³; magnetic loss component) spectrum of the NSS was aimed to utilize. Referring to the previous finding that Dispersion DIII is originated from a magneto-elastic effect, several magnetic composite sheets were prepared using various alloy flakes with different saturation magnetostriction (λs), and their frequency (fr(DIII)) and magnitude (μâ³(DIII)) of Dispersion DIII were investigated. It was found that the NSS containing flakes with higher λs exhibited higher fr(DIII) and higher μâ³(DIII)/μâ³(DII), which was ratio of μâ³(DIII) to the magnitude of Dispersion DII (μâ³(DII)). The fr(DIII) for the NSS having the highest λs containing Fe-Co alloy flake reached 7.45 GHz and μⳠin the 5 GHz band was approximately twice as high as the conventional NSS containing Fe-Si-Al alloy flake. For transmission attenuation power ratio (Rtp) when an NSS was placed on a microstrip line with characteristic impedance of 50 Ω, NSS with larger fr(DIII)2 · μâ³(DIII) â Ms2 (Ms: saturation magnetization), which theoretically gave the frequency limit of imaginary permeability for a thin film, exhibited larger Rtp in the low SHF band. These results suggested that an NSS containing a magnetic flake material with both large λs and Ms was suitable for suppressing low SHF band noises.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
Toshiyuki Igarashi, Koichi Kondo, Shigeyoshi Yoshida,