I've been told by people I trust that the coaxial cable between an amplifier
and an antenna must be a minimum of 18 inches long. I personally recom-
mend doubling that minimum so any bends in the cable will be gentle.
Installing for intermittent use
The primary reason for installing an amplifier that you only use intermittently
is purely one of neighborly consideration. Providing you followed my advice
about extending your range in Chapter 3, your system, including an amplifier,
won't exceed the FCC power-output regulations. Even so, when you find your-
self parked three feet from another hotspot user, it's possible that your high-
output setup might cause interference problems for your neighbors.
By mounting the amplifier near the termination point of your coax, you can
simply disconnect your antenna cable and pigtail from the amplifier and con-
nect the pigtail directly to the antenna cable, bypassing the amplifier. This
arrangement gives you the benefit of a high-gain antenna without creating an
interference problem for your neighbors every time you use Wi-Fi.
Be sure that your amplifier is powered down before you disconnect the coax-
ial cables. Failing to do so might damage the amplifier.
Installing for constant use
A permanent, constant-use installation differs from an intermittent installa-
tion only in the options available to you for slightly increasing the efficiency
of your amplifier and antenna. By locating your amplifier close to your antenna,
you can limit attenuation to a level that's nearly immeasurable. If you're using
LMR-400 coaxial cable (as I've suggested) and your cable run is, say, 20 feet,
then your signal-strength loss is approximately 1.34dB. This is by no means
excessive -- but you can reduce loss to less than .25dB if you place your
amplifier 3 feet from the antenna.
Because you don't need to connect and disconnect from the amplifier, there's
no reason to locate it near the area you'll most likely use your computer and
you're free to mount it anywhere that's convenient. You might even, in this
type of installation, be able to mount your amplifier in an area that's both
nearer the antenna and closer to the power source.
If a constant-use installation is something you're considering, you might also
want to make sure you have an alternate method of connecting with hotspots
just in case you do run across a situation in which your amplifier is causing
problems for your neighbors.
Chapter 4: Putting Your Gear Together
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