Granular thin films with high RF permeability

Abstract

Owing to high resistivity and high inplane uniaxial anisotropy, granular films are known to exhibit high permeability at radio frequencies. But this granular resistivity is not high enough to suppress eddy current when they are used at gigahertz frequencies. Recent developments to solve this problem are described. One is patterning the granular films. It is effective to control the inplane anisotropy and to suppress inplane eddy current. Another is deposition of granular films by evaporation. A peculiar fiber structure is formed for which very high resistivity and anisotropy are realized. Finally, a study of using these films as near-field electromagnetic noise absorbers is described, and it is demonstrated that they have high potential as micrometer-scale noise absorbing elements in the gigahertz frequency range.

RF Power Absorption Enhancement of Magnetic Composites with Conductive Grid

“…To reduce these complicated EMI, conduction noises and coupling between neighbor transmission signals in electronic circuits and devices, a few kinds of considerations are essential such as the volume, high resistivity, and the high magnetic loss of the magnetic materials as an EMI countermeasure materials in near field. The magnetic films and composites as an electromagnetic noise absorber have been conventionally employed [1][2][3]. In general, the magnetic composite which is composed of magnetic filler and nonmagnetic matrix has been studied for the applications of near-field electromagnetic noise suppression [4].…”

Evaluation of tailored magnetic composite films for near-field electromagnetic noise suppression

“…In near-field EM countermeasure between the integrated circuits and devices, the noise suppression due to the electromagnetic absorption could be more effective than those of the electromagnetic shielding. In order to avoid the EM interference coupling between signal lines and to improve the signal integrity of the electronic devices in the radio frequency (RF) region, the conduction noise should be reduced or removed on signal transmission line [2][3][4][5][6][7][8]. In general, the electromagnetic noise suppression is governed by materials or structures, which dissipates a portion of incident EM energy into internal heat.…”

“…The impedance from the radiation source in the near field will vary with the addition of equivalent resistance to the transmission path, making for a complex phenomenon. To suppress the EM noise and signal interference between the signal lines, the loss generations due to the ferromagnetic resonance (FMR) in ferromagnetic metallic and insulative materials and the relaxations are one of the good countermeasures for the absorption of EM conduction noise emission on transmission line [2][3][4][5][6][7][8]11]. The magnetic materials should have suitable working at a specific frequency or a broadband frequency region by control the magnetic loss frequency.…”

Granulare ultradünne Nanoschichtsysteme Fe/FeO auf Aluminiumsubstrat, Modellierung einer 1 D ultradünnen granularen Schicht für elektromagnetische Verträglichkeitsanwendungen (EMV) der Flachbandkabeltechnik

“…Jedoch beziehen sich diese Betrachtungen auf kristalline Schichten und nicht auf reale granulare Strukturen. Granulare Strukturen sollen [ 2 ] eine höhere Absorption der elektromagnetischen Energie realisieren können als kristalline Schichten.…”