why use magnetic beads for high frequency signal?

[walkrain]

The day, when doing meter measuring, I use magnetic beads for high-frequency signal, through the book, i know when the high-frequency signal through the magnetic beads, the energy can be converted to heat, and losses. But when i calculate it by circuit analysis theory, i found when HF signal through the magnetic beads, only reduce the peak voltage, it can't changes the frequency of the voltage, so, i want to know since it can't change the frequency of the voltage, why i use it ?

 

[keith1200rs]

Ferrite beads increase the wire inductance. That increases the impedance of the wire at high frequencies and reduces the high frequency signals passing down the wire. It has nothing to do with heat.

Keith

 

[walkrain]

Ferrite beads increase the wire inductance. That increases the impedance of the wire at high frequencies and reduces the high frequency signals passing down the wire. It has nothing to do with heat.

Keith

I will do a frequency analysis, and thank you for your answer.

 

[Mad I.D.]

Ferrite beads increase the wire inductance. That increases the impedance of the wire at high frequencies and reduces the high frequency signals passing down the wire. It has nothing to do with heat.
Keith

Quotation from https://en.wikipedia.org/wiki/Ferrite_bead :
Ferrite beads employ the mechanism of high dissipation of high frequency currents in a ferrite to build high frequency noise suppression devices.

 

[keith1200rs]

Ferrite beads increase the wire inductance. That increases the impedance of the wire at high frequencies and reduces the high frequency signals passing down the wire. It has nothing to do with heat.
Keith

Quotation from https://en.wikipedia.org/wiki/Ferrite_bead :
Ferrite beads employ the mechanism of high dissipation of high frequency currents in a ferrite to build high frequency noise suppression devices.

You are right, although it depends on the frequency. At lower frequencies the reactance dominates, at higher frequencies the resistance does. Either way, you are unlikely to notice any heat.

It probably makes more sense to view a Ferrite bead as an inductor that turns resistive at very high frequencies. If you start to consider it as something which dissipates energy as heat then you also need to do the same with all resistors, such as in an RC filter, which probably isn't a useful way of analysing things.

Keith.