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
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
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 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
> 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?
> freebsd-mobile at freebsd.org mailing list
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