GE GFK-2489 - Manual (Page 141)

6-8 TranSphere TS Wireless Extended Range IP Networking Transceivers – January 2008 GFK-2489
6
Antenna and Feedline Selection
Antennas
The equipment can be used with a number of antennas. The antenna type used depends on
the physical size and layout of a system.
In general, an omnidirectional antenna (see below) is used at the AP sta tion site. This
provides equal coverage to all of the remote sites.
Antenna polarization is important. The wrong polarization causes a signal reduction of 20 dB
or more. Most systems using a gain-type omnidirectional antenna at the AP station employ
vertical polarization (elements oriented perpendicular to the horizon) of the signal; therefore,
the Remote antenna(s) must also be vertically polarized.
Horizontally polarized omnidirectional antennas are also available.
At remote sites, and for radios in point-to-point LANs, a directional Yagi (shown below)
antenna is generally recommended to minimize interference to and from other radio systems.
Antennas are available from a number of manufacturers.
It is essential that all antenna systems incorporate appropriate lightning protection.
Information on lightning protection and grounding considerations can be obtained from the
Polyphaser Corporation (www.polyphaser.com). The firm’s Web site offers free engineering
notes, as well as information on lightning protection devices.