Wireless Hacks. 1917 IndustrialStrength Tips and Tools [Electronic resources] نسخه متنی

Hack 66 Pigtails

Use a short length of feed line to connect your
wireless device to an antenna.

While
some wireless equipment has no external antenna connector available
at all, many devices ship with a tiny, non-standard port to
accommodate an external antenna. Most antennas use a standard
microwave connector [Hack #63]. Typically, to connect
one to the other, you need a short length of cable with one of each
sort of connector. This connector is commonly referred to as a
pigtail adapter. A pigtail in all its glory is
depicted in Figure 4-29.

Pigtails are available from a number of sources. They typically sell
for $10 to $20, depending on the length and type of cable, and what
connectors you need on each end. Be sure that you know what sort of
connector [Hack #65] you need on the card
side as well as on the antenna side. Most 802.11 manufacturers will
also sell you a pigtail adapter for a phenomenally inflated price
($80 to $100 or more, for virtually the same piece of cable).

Pigtails have extremely high loss compared to a larger cable (such as
LMR400), and usually use a cable such as LMR100 or LMR195. It is
generally a good idea to keep your pigtail lengths as short as
possible, and run larger, lower-loss cable for the bulk of your
antenna run. Be sure to observe the type of connector, as well as the
gender (male or female) that you need for either end. Adapters and
gender changers can help in a pinch, but remember that excessive
adapters will add unnecessary loss to your overall system.

The client card end of a pigtail is typically available in straight
or right-angle versions. Both connectors have identical loss, but the
best choice depends on the physical layout of your equipment. Most
times, a right-angle connector is preferred, but depending on how
your cable needs to run, a straight connector may work better. Also
remember that the small end of the pigtail is very fragile, and will
snap easily if pulled or forced into the connector. Use care when
installing or removing pigtails, and whenever possible, tie off the
cable to help eliminate cable stress on the connector. It is common
to use a nylon zip tie to fasten the cable to the card itself, the
chassis, or another stationary part.

When you are sure of the sort of pigtail you need for your
application, consult the list of hardware vendors
[Hack #67].