Robert from Charleston, North Carolina, called asking how to extend a
wireless
network's coverage.

The typical WiFi card or access point offers a 2.2dBI antenna. That's
enough
power to reach about 150 feet. To go farther you'll need to increase
the
gain. There are two ways to do that.


+ Add an amplifier.

+ Add a high-gain antenna.

The problem with using an amplifier is that it will increase the output
of your WiFi access point, but not improve its reception. In other
words,
it only improves reception one-way. Fortunately, adding a passive
antenna
is cheaper and more effective.

Unfortunately, adding an external antenna to your WiFi router is still
a
black art. Each WiFi access point (WAP) manufacturer uses a different
external
connector -- for those WAPs that have external connectors, that is. To
connect
an external antenna you'll first need to make sure your WAP has an
external
connector, then you'll need to find the right "pigtail" for that
device.
Seattle Wireless has an excellent pigtail guide.

Once you have the right pigtail for your WAP, you'll need a cable to
connect
to your antenna. Buy a low-impedance cable designed for this purpose. I
recommend LMR 400 for anything over a few feet. The impedance of normal
coaxial cable is too high for these low power WiFi signals.

Then you'll have to choose an antenna. WiFi antennas come in
directional
and omnidirectional flavors. Directional antennas can increase the
range
much farther, but only in one direction.

NetNimble Wireless Products offers excellent cable and antenna choices.
For indoor use, its 5.5dBi Omnidirectional antenna is $49 and comes
with
connectors for the most popular WAPs. For a little more, you can buy
its
10dBi directional panel to nearly double your range in a single
direction.
Using an antenna on both ends (the WAP and computer) can increase range
even more.

Coincidentally, I did this very upgrade as part of our Digital Digs
series
on The Screen Savers last month. My Apple Airport WAP works pretty well
inside the house, but there's no signal at all to the rest of the
property.
I wanted to get a signal to my barn about 200 feet away and to a little
nearby shade tree where I like to lie in a hammock. Using roof-mounted
directional
(http://www.buffalotech.com/wireless/...irectional.php)
or omnidirectional antennas from Buffalo Technology
(http://www.buffalotech.com/),
I was easily able to extend my WiFi to every part of the farm.

One thing to keep in mind, however, is that when you're broadcasting
your
WiFi to a greater area, it's easier for people to steal your signal.
Make
sure you turn on WAP encryption and password protection to deter
hackers
from sneaking into your system.


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