weak signal

richard childers / kg6hac fscked at pacbell.net
Sun Feb 22 13:12:23 PST 2004


Yes, your 2.4 gHz telephone may well interfere with your 2.4 gHz 
wireless network.

I've noticed that using microwave ovens sometimes interrupts the signal, 

Workarounds relate to how you position your antennas in relation to one 
another, as well as what you do to relocate or shield potential sources 
of interference.

In general, both transmitting and receiving antennae should be adjusted 
to be parallel to one another.

Specifically, in this case, if your WAP is in the basement and your 
wireless network clients are on the first floor, you would want to 
orient your antenna elements so that they were horizontal, so that their 
signal would be directed upwards, towards the clients .... downwards, 
towards the basement ... and outwards, towards the neighbors' houses, on 
both sides ... in a circle, radiating outwards, with your antenna at the 

Because, to the best of my knowledge, most 802.11b client cards - being 
PCMCIA-based - are inserted into horizontally aligned bays in the sides 
of laptops which sit on flat surfaces, it can be said sweepingly that 
most of the client card antennae are horizontally aligned - or, as we 
say in the radio business, their signals are -horizontally polarized-.

However, because there is still some randomness in how the client cards 
are aligned - north-south, east-west, or some variation thereof - there 
is still a great deal of potential for signal loss, because these 
secondary details of antenna alignment also translate into alignment, or 
lack thereof, of the sending and receiving antennae, and, consequently, 
polarization, or lack thereof - with associated signal strength loss.

A third factor is proximity. A WAP sitting on a table in the basement is 
five feet farther from its clients than it has to be. If you can perch 
the WAP atop a rack, or even attach the WAP directly to the ceiling, you 
are eliminating a few feet of unnecessary loss of what is already a 
fairly low strength signal.

And there is a fourth factor - intervening equipment and materials. Some 
materials - such as concrete with a web of steel reinforcing ( 'rebar' ) 
in the center, or concrete with a high iron content, will absorb the 
signal. So will a file cabinet that is in the line of sight (although 
the top of the file cabinet would be a good place for the WAP).

Having eliminated all of these factors, if your signal is still weak, 
you may wish to look into add-on antennas for your wireless card. The 
high-end cards all have antenna jacks which are more or less industry 
standard and with a little effort, one can locate small Yagi, and other, 
antennae, which are designed for the 2.4 gHz spectrum. (The notorious 
Pringles can antenna is only one of many available - see Google for 

Making sure your antenna is solidly attached and that no leads are loose 
in the housing would not hurt, before you go replacing or augmenting 
your existing antenna, of course.

Complementarily, everything described above can be used to shield 
multiple 2.4 gHz sources from one another, where desirable. Microwave 
ovens can be shoved up next to file cabinets, on a side away from 
wireless networks, for example, and wireless telephone systems can be 
similarly located so that their signals are less likely to overlap with 
your WAP clients - perhaps the telephone transceiver can be put 
upstairs, or in one corner of the house, on a shelf, as far away from 
the WAP as possible, for example.

Having put all this solid information out for free, let me add that 
Daemonized Networking Services handles exactly this sort of installation 
and administration, for both business and residential customers, 
throughout the San Francisco Bay Area - please don't hesitate to call if 
we can be of service, professionally.  (-;


-- richard


Richard Childers / Senior Engineer
Daemonized Networking Services
945 Taraval Street, #105
San Francisco, CA 94116 USA

Neil Camara wrote:

> Hey guys,
> I am using Netgear MA311 PCI card on FreeBSD as my access point. It's 
> down in my basement. I am only getting 2 bars in my workstation 
> situated in 1st floor. Is there a way to make the signal much more 
> stronger?
> I also have noticed that my connection gets drop when I using Uniden 
> PowerMax 2.4 ghz telephone. Are there any issues? Is there a work around?
> Thanks.
> Neil
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