Wireless PCI antenna in an unfit place.

Hello, i realized a WLAN in my small apartment. Works ok, the only thing
is that i have my desktop in a bad place for receiving WLAN signal.

I receive it with a PCI WLAN card. The antenna is on the back and the
case is very close to the (big and thick) wall, on its right a wooden
drawer, on the left a (small) sub woofer. The AP is about 10m on the
right, with no other obstacles in the line of sight except from the
above mentioned wooden drawer.
My hypothesis is that the wire web that's usually on the back of the PC
causes some interference/shielding, as does the wall and the case
itself. The wooden drawer shouldn't be much trouble, am I right?

Not to mention that pulling the PC 20cm or so apart from the wall the
signal becomes VERY GOOD. Note: my laptop on the side of the pc or ON
the drawer gets an excellent signal.

Now, the question: how can I workaround this problem, possibly in a
frugal way?
I've see cantennas and parabolas, but I doubt they will do the job. One
thing that'd work would be to get an rf cable and place the antenna ON
the drawer, but I would like to spare that money if possible.
I was thinking about shielding other cables... But this being a problem
of shielding from the wall, I doubt it will do the job...

Any advice?

Thanks

Stefano

On Sun, 17 Dec 2006 21:36:33 +0100, Stefano wrote:

> Hello, i realized a WLAN in my small apartment. Works ok, the only thing
> is that i have my desktop in a bad place for receiving WLAN signal.
>
> I receive it with a PCI WLAN card. The antenna is on the back and the
> case is very close to the (big and thick) wall, on its right a wooden
> drawer, on the left a (small) sub woofer. The AP is about 10m on the
> right, with no other obstacles in the line of sight except from the
> above mentioned wooden drawer.
> My hypothesis is that the wire web that's usually on the back of the PC
> causes some interference/shielding, as does the wall and the case
> itself. The wooden drawer shouldn't be much trouble, am I right?
>
> Not to mention that pulling the PC 20cm or so apart from the wall the
> signal becomes VERY GOOD. Note: my laptop on the side of the pc or ON
> the drawer gets an excellent signal.
>
> Now, the question: how can I workaround this problem, possibly in a
> frugal way?
> I've see cantennas and parabolas, but I doubt they will do the job. One
> thing that'd work would be to get an rf cable and place the antenna ON
> the drawer, but I would like to spare that money if possible.
> I was thinking about shielding other cables... But this being a problem
> of shielding from the wall, I doubt it will do the job...
>
> Any advice?
>
> Thanks
>
> Stefano

This is what your after... http://www.wifi-antennas.com/mobile-antenna.htm
Stick it on the drawer or ontop of the PC case.

Doz

Are you sure that you can't re-position your pc? Sounds like it's
close to working.

How is the pc's antenna pointing? In most circumstances you want it
pointing up. It probably has a "doughnut" shaped pickup pattern and
if it has the antenna tip rotated and pointing AT the router/access
point, then it would actually be in the dead spot. Seems
counter-intuitive, but imagine it has a doughnut on a skewer and make
sure you are not pointing the "hole" at your source.

Also, there are designs for simple reflectors you can make that help
reception. Google for "EZ-10 reflector"

If you can't make the current antenna work, then an external antenna,
as posted above, seems like what you want. Probably doesn't need much
gain or directionality (depending on cable loss). Mostly you are
just moving the antenna away from the back of the pc.

Two cautions:
1) Make sure that the antenna connector you buy matches your PCI card.
Check the documentation for the card or the manufacturer's site.

2) Cable loss is a factor. Roughly, the shorter and thicker the
antenna cable, the better. If I could get away with a 24" or 36" cable,
I would choose that one over a four or six foot cable.
Better yet, find out what the cable type is and find out what it's loss
is, if you can.



Steve

Stefano <oppenheimer@bomb.ne> wrote:

> Hello, i realized a WLAN in my small apartment. Works ok, the only thing
> is that i have my desktop in a bad place for receiving WLAN signal.

I have used the "Hawking HAI6SDA Directional 6dBi 2.4GHz Antenna" with good
success on a Netgear WG311 PCI card. $20-30.
<http://www.hawkingtech.com/products/productlist.php?CatID=32&FamID=58&ProdID=122>

Hawking and others have USB clients built into antennas. That might be
handy.
<http://www.hawkingtech.com/products/productlist.php?CatID=32&FamID=60&ProdID=280>

Within a single room, any USB adapter would let you get the antenna
positioned in a better place. I see the Linksys WUSB11 for $7 in the US.
Netgear WG111 for $12.

> Now, the question: how can I workaround this problem, possibly in a
> frugal way?

If you can't relocate the PC, can you relocate or re-orient the AP?

I would favor a free reflector on the PC and the AP.
http://www.freeantennas.com EZ-12 Windsurfer.

Remember that you want the PC and AP antennas pointed broadside to each
other, not end-on. The antenna pattern is like a donut on a stick, with
the direction off the tip of the antenna being the weakest signal.

--
---
Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5

Thanks everyone.

In the end I solved the problem with two unused SMA connectors I
happened to find at the lab I work, to manufacture a cable to
reposition the antenna.
The only problem was the cable, cause I could not "borrow" a 2.4Ghz
cable as well.
So I simply tried with a coax BNC cable (the ones used for
oscilloscopes, if you used one). Soldering was a mess, especially cause
I had to invert the SMA central pin from male to female.

Being in an already good spot, I kept the cable very short. It's maybe
less than 2ft now. As soon as I connected it the signal was better, but
it will go down to nothing from time to time in an unrealiable way. So
my last guess before throwing everything away was to put some aluminum
foil around soldered spots at the cable ends, and that surprisingly
worked wery well. Now I consistently get a "very good" signal.
I may add a cantenna or parabola on either the AP or th receiver to
reach "excellent".

Thanks for all suggestions.

Stefano

A regular paper clip can work as the pin in a female SMA connector.
The wire for the paper clip is just the right diameter.

Stefano wrote:
> Thanks everyone.
>
> In the end I solved the problem with two unused SMA connectors I
> happened to find at the lab I work, to manufacture a cable to
> reposition the antenna.
> The only problem was the cable, cause I could not "borrow" a 2.4Ghz
> cable as well.
> So I simply tried with a coax BNC cable (the ones used for
> oscilloscopes, if you used one). Soldering was a mess, especially cause
> I had to invert the SMA central pin from male to female.
>
> Being in an already good spot, I kept the cable very short. It's maybe
> less than 2ft now. As soon as I connected it the signal was better, but
> it will go down to nothing from time to time in an unrealiable way. So
> my last guess before throwing everything away was to put some aluminum
> foil around soldered spots at the cable ends, and that surprisingly
> worked wery well. Now I consistently get a "very good" signal.
> I may add a cantenna or parabola on either the AP or th receiver to
> reach "excellent".
>
> Thanks for all suggestions.
>
> Stefano