On Thu, 31 Mar 2005 10:30:43 -0500, "Skip Gundlach" skipgundlach sez
use my name at earthlink dot fishcatcher (net) - with apologies for
the spamtrap wrote:

I'm looking for experience with external antenna solutions to very flaky
wifi access on the boat. There's every sort of hub range improver (get your
signal out to others better) but I don't see much, if anything of the other
way around.
One solution is to use a wifi pcmcia card that allows external
antennas. I use the Orinoco Gold Classic now marketed by Agere. When
I bought it, it was one of the very few cards supported by
Netstumbler, which I wanted to play with. Now there are a fair
number, but I'm satisfied with the Orinoco. Pretty old technology
now, though. Probably not up to date with the latest security
improvements. It does support an external antenna; few do. Without
an antenna, your range is variable, typically from a hundred feet to a
few hundred yards.

As for antennae, many people recommend what are called "Cantennas"
about the size and shape of a Pringles can. The original model
actually was a Pringles can. These are yagis, with some wave guide
types, that look very similar and seem to have similar specs and are
widely available on Ebay. These are OK in the slip, but useless at
anchor. They are highly directional, with only about a 30-45 degree
beam spread. They claim 12-17 db gain. There are omni directional
whips made for car use and boast about 7 db gain, with a magnetic
base. I recently saw a 4 ft pole-mount whip omni antenna that claims
12 db gain. I haven't actually tried any of these antennae yet, I'm
still in research mode. 802.11b and 802.11g use the same antenna.
802.11a uses a different frequency, but you won't see many 802.11a
networks.

The tricky part are the connectors. Each antenna has a connector
(commonly N type), each card has a connector (varies by brand, with MC
type perhaps being most commonly seen in the field.) They are seldom
compatible. The antenna vendors offer pigtails for the conversion.
The typical pigtail is about 5 feet long. This is not acceptable for
boat use, IMHO. First 5 feet is not long enough, but the cable
normally used is fairly high loss. I don't have the specs onhand, but
if you need a longer cable, research low loss cables. Don't just
daisy chain a couple of 5 footers. Also, the connectors on many cards
are notoriously unreliable. They wear a bit every time you remove and
replace the cable, sometimes needing repair or replacement after about
20 uses. One solution is to buy a short (1 foot) pigtail and "glue"
it to the card with silicone. Then use whatever length of low loss
cable you need to get to the antenna.

Hope this helps;

Glen
__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at world wide wiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/