Shielding a wireless signal

Hi,
I am interested in this topic mainly with regards to Bluetooth devices
but I presume it is equally relevant to wireless in general.

Can I shield my radio emitting device on one side, so that it only
emits in one direction? In other words, what materials could I put in
front of my router/bluetooth device to attenuate the signal?
Thanks,
Mike

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
> Hi,
> I am interested in this topic mainly with regards to Bluetooth
devices
> but I presume it is equally relevant to wireless in general.
>
> Can I shield my radio emitting device on one side, so that it only
> emits in one direction? In other words, what materials could I put
in
> front of my router/bluetooth device to attenuate the signal?
> Thanks,
> Mike

Aluminum foil does a pretty good job

On 7 Jan 2005 03:53:54 -0800, (E-Mail Removed) wrote:

>I am interested in this topic mainly with regards to Bluetooth devices
>but I presume it is equally relevant to wireless in general.
>
>Can I shield my radio emitting device on one side, so that it only
>emits in one direction? In other words, what materials could I put in
>front of my router/bluetooth device to attenuate the signal?
>Thanks,
>Mike

It would be helpful if you would disclose what you're trying to
accomplish or what problem you're trying to solve.

You should distinguish between absorption and reflection. Both will
block a signal but in different ways. A piece of sheet metal, wire
mesh, or aluminium foil, will prevent the signal from going through,
but will also reflect the signal to who knows where. If you're trying
to control the distribution of the signal, this is not a great way to
do it.

Absorption converts the RF to heat. A piece of carbon doped
anti-static foam works nicely. A wet towel works well at 2.4GHz
because water absorbs RF. If you like spending money, Eccosorb:
http://www.eccosorb.com/catalog/eccosorb/anw.asp

For the true fanatics, we have frequency selective wallpaper:
http://www.newscientist.com/article.ns?id=dn6240


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558

Taking a moment's reflection, (E-Mail Removed) mused:
|
| I am interested in this topic mainly with regards to Bluetooth devices
| but I presume it is equally relevant to wireless in general.

Is it to direct the signal, or to contain the signal? If the latter,
note that Bluetooth's range is fairly limited anyway.

Thanks for the useful info. Though I'm not too sure what you mean by
'carbon doped'.

Mike

On 9 Jan 2005 12:59:21 -0800, (E-Mail Removed) wrote:

>Thanks for the useful info. Though I'm not too sure what you mean by
>'carbon doped'.

Foam loaded with carbon granules. Polystyrene carbon foam is an fair
absorber of RF. That's what RF dummy loads are made from. They are
essentially resistors that convert RF energy into heat. The military
paints their airplanes with a form of carbon foam plus ferrite to
reduce radar reflections. Ferrite doped material is better for a
wider range of (lower) frequencies.
http://tdkrfsolutions.com/absorbers.htm
The common (cheap) black carbon conductive foam sheets that are often
used for anti-static holders for intergrated circuits work well
enough.
http://www.contacteast.com/product/g...parent_id=3044


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558