Re: Re: Ferrite vs. WI-FI?

December 30, 2009

It may not be what the original post had in mind, but

if you're in a situation where the wireless transmission is

well shielded (neighbor with shared transformer, with

high metal fence or adobe wall in between) then

possibly the dominant source of Wi-Fi is through the

wires. (I think at those frequencies the common mode

will die out very quick, but if there are widely separated

wires or current loops you can get differential mode

coupling, and this could travel fairly far?).

Most ferrites are not rated above 1GHz I think, but

if you can get some 2.4GHz ones it might help.

HOWEVER, I've read that ferrites generally saturate

(become useless) above 5 amps of current (at any frequency)

in the wire.

That means putting it on your service wires (if you can

get them that big) is a waste unless your power is off

(or you're using less than 600 watts). The obvious

place to put one is on the neighbor's router and computer

power cords, but again if there are wiring errors there may be transmission

from wireless to wire (luckily this should be

easy to filter because of the high impedance; but the filter

has to have a high quality capacitor with low inductance--i.e. short--

leads). If you can measure

an increase in Wi-Fi at your phone then put the ferrites on each

of your phone wires.

But probably more often the problem is from the airborne Wi-Fi.

Bill

On Wed, Dec 30, 2009 at 7:35 PM, cris_aov <cris_aov@...> wrote:

>

> Yes ferrite bead and torroids among others are mostly used to suppress RF

> on cables, but they also make ferrite sheets.

>

> Even at several feet away youll be geting exposed to the radiation from the

> wi-fi, remember that wifi units can extend their signal far, plus at close

> distances youll also be getting the RFI/EMI and AC electrical radiation from

> the unit itself on top of the actual rf from the wi-fi signal.

>

Recommended Posts