high-gain antennas can do better with an external high-gain antenna.
There are two types of high-gain antennas:
· Omnidirectional: Most antennas are omnidirectional -- covering a
360-degree area -- and that includes the most common high-gain
antennas that are suitable for travel. Note, however, that an omni-
directional signal is not spherical.
· Directional: The difference between omnidirectional and direc-
tional antennas is like the difference between (respectively) a
lantern and a flashlight. A lantern casts light in a full circle; a flash-
light focuses its light as a narrow beam.
The phrase antenna gain refers to the focus of the signal or field. A high-
gain antenna has a tightly focused field; a low-gain antenna has a widely
focused field. A high-gain antenna, therefore, isn't necessarily more pow-
erful than a standard-gain antenna. In fact, there's really no energy
increase connected with a high-gain antenna -- it's just that the existing
energy is more focused.
Amplifying output: If you've found that a high-output 200mW laptop
adapter doesn't quite cut the mustard (or you're just plain power-
hungry), there are several wireless amplifiers on the market that range
in output from 200mW to 1000mW (1 Watt).
Do not -- I repeat, do not -- attempt to amplify the output of a high-output
adapter. You'll only fry the amplifier. Amplifiers are designed to handle the
input power of a standard wireless adapter -- that is, with a range of
32mW to 63mW.
Combining increased output and gain: By far the most powerful config-
uration for extending your Wi-Fi range is the combination of a high-
output amplifier and a high-gain antenna. You'll be happy to know that
several vendors sell complete kits that include the adapter, the amplifier,
and a high-gain antenna.
Comparing directional and
omni-directional antennas
A directional antenna, as its name suggests, picks up and transmits a signal
from -- and in -- a particular direction. Here are some attributes typical to a
directional antenna:
Focused beam width: With its energy directed into a relatively narrow
vertical and horizontal beam width, a directional antenna can be
extremely efficient -- it's a high-gain antenna almost by definition. The
higher its rated gain, the more narrowly focused the beam width.
Reduced interference: Because interference may be centered in an area
not covered by the narrow beam width, and because the energy is more
Chapter 3: Gearing Up
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