Runway shaped magnetic ring function main is elimination exists Yu transmission line structure (circuit) in the of RF noise, RF energy is overlay in DC transmission level Shang of Exchange sine wave components, DC components is need of useful signal, and RF RF energy is is useless of electromagnetic interference along line transmission and radiation (EMI). to elimination these not need of signal energy, using tablets type magnetic beads played high frequency resistance of role (attenuation device), the devices allows DC signal through, Filtered AC signal. usually high frequency signals for the 30MHz, however, low-frequency signals will be under the influence of chip beads.