| 摘要 |
A bead type noise filter according to the present invention is constituted by a magnetic core 1 formed of Mn-Zn ferrite having its resistivity increased so as to improve a high frequency characteristic, and having its permittivity lowered, and thereby can successfully suppress radiation noises without distorting the waveform of transmission signals. The magnetic core 1 constituting the bead type noise filter is formed of a high resistivity soft magnetic material, is shaped cylindrical, and has at least one through-hole 1a so as to form a closed magnetic path, and the bead type noise filter is attached on a signal line 2 such that the signal line 2 is inserted through the through-hole 1a. The soft magnetic material has a real part of complex relative permittivity ranging from 1,000 up to 20,000 at 1 kHz and 50 or lower at 1 MHz, and has a resistivity of 150 OMEGA m or higher. <IMAGE>
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