more powerful than built-in wi-fi adapters (200–300
milliwatts is typical) and frequently offer an external
antenna connection. USB wi-fi adapters are now
available with 500-milliwatt power output, but be
leery of using USB adapters on older computers that
may have USB 1.0 ports. The slower USB 1.0 port
noticeably reduces the overall performance of the
wi-fi connection, and the port may not be able to
supply sufficient power for the USB adapter when
transmitting. Keep in mind that access points almost
always use vertical antennas. If the onboard wi-fi
antenna is horizontal, as is typically the case with
those built into PCMCIA cards, the antennas are
said to be cross-polarized. This can result in a serious
reduction in signal strength and should be avoided
if you’re seeking maximum performance.
USB wi-fi adapters have other advantages besides
potentially higher transmitter power. A USB adapter
can be connected with a USB cable up to 16 feet in
Courtesy of 5Mile WIFI
Above: A little less than 3 inches in length, the 5Mile WIFI
enclosure contains both the wi-fi adapter and the bidirectional
amplifier that gives a boost to received and transmitted
signals. Red and green LEDs monitor receiver and transmitter
activity. Right: The 5Mile WIFI package includes a 38-inch
omnidirectional external antenna that provides 9dB of gain
and a 25-foot length of low-loss antenna cable.
www.PilotCruiser.com
866-372-2190
An exciting new design for
long range cruising by Iver
Franzen, Naval Architect
PilotCruiser® 57
ELECTRONICS
Joe Minick
length with no loss in data
speed. In many instances this
will allow the USB adapter,
complete with its built-in
antenna, to be temporarily
placed outside the vessel,
which can significantly improve
performance. These adapters
usually aren’t weatherproof,
so this type of setup must be
temporary, but it works well
for many. In addition, several
USB adapters are available
with a connection for an
external antenna.
Permanently mounted
external antennas still offer
the best all-around performance
and convenience, but their
installation requires a bit of
planning to maximize wi-fi performance. Locate the
antenna as high and as far from other metal objects
as possible while keeping in mind the loss in signal
strength associated with long runs of antenna cable.
Low-loss antenna cable, such as LMR-400, loses
about 6.8dB per 100 feet; RG- 58 cable, typically
used for installations of marine VHF antennas, will
lose more than 25dB over the same length. It’s quite
possible to install an antenna with 9–10dB of gain
and to lose only a fraction of that gain by connecting
it with a low-loss cable.
5MILEWIFI ADAPTER
Every now and then a product comes along that
seems to fit just about right in the marine environment.
The 5MileWIFI adapter is reportedly finding a home
on quite a few boats these days, so we acquired one to
