Increased power: The average output of a standard laptop wireless
adapter is between 31.6mW and 63.2mW -- sufficient for surfing the Net
while sipping latte -- but when you're berthed in the back row and there's
an ocean of trucks or RVs between you and the access point, more power
may be the answer. Fortunately, several adapter models, all seemingly
built around the same basic design, boast an output of 200mW.
When shopping for an adapter, you're bound to see power rated in two
ways: milliwatts (mW) and in decibels above or below 1mW (dBm). You'll
also see antenna gain referenced, usually, as decibels relative to a theo-
retical isotropic antenna (dBi). Sounds a bit like Star Trek, doesn't it? But
here's the practical gist: When you're comparing two devices, remember
that an increase of 3 dBm (or 3 dBi) indicates a doubling of the power
level (also called antenna gain); a decrease of 3 dBm (or 3 dBi) means a
halving of the power level. For example 31.6mW is expressed as 15 dBm,
63.2mW is expressed as 18 dBm, and 200mW is expressed as (approxi-
mately) 23 dBm, which is pretty powerful either way.
You may find, while wandering the World Wide Web, wireless adapters
that claim a power output of 300mW or higher. These adapters aren't
meant for use in a laptop. Higher power means higher heat; you could fry
your laptop's delicate innards like a shoe-leather steak.
Increased antenna gain: A high-gain antenna uses a more focused
energy to pull in signals that a standard antenna may not even be able to
detect. I don't fully understand antenna gain -- and only a handful of
people (mainly employed by NASA) can claim to know someone who
does -- but I'm content if it works as advertised.
Several laptop adapters currently available incorporate one, or both, of the
methods that improve adapter performance. Some are PC-card adapters;
others are USB adapters. Whichever you use is purely your own preference. I
prefer to travel with a PC-card adapter; you may, for any number of reasons,
want a USB-powered device. Table 3-2 lists some of these adapters in no par-
ticular order. (Okay, bias being what it is, my favorite is listed first!)
Table 3-2
Performance-Enhancing Adapters
Adapter
Power and/
Highlights
or Increased
Antenna Gain
SMC2532W-B
This high-output card
Other PC card adapters
boasts 200mW (23 dBm)
assembled by other manufac-
(Yes, it's my favorite
of power and comes
turers are based around the
PC card adapter.)
standard with a remov-
same Prism 2.5 chipset, but I
able 5.5 dBi high-gain
like this SMC adapter best.
802.11b standard
antenna, combining both
One reason, its superb perfor-
methods of performance
mance notwithstanding, is
enhancement. For more
that it's widely available from
Part I: The Wonderful World of Wireless Fidelity
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