Extreme Networks Extreme Wireless, Site Preparation And Installation Manual, Page: 8 / 147

Table 3: Antennas for Wireless Network Configurations
Network Configuration Description Antenna Type
LAN-to-LAN Point-to-Point This is a wireless link between two WDS
APs that connects two separate wired
LANs. (WDS APs are configured to
operate as Workgroup bridges.) Directional antennas
LAN-to-LAN Point-to-Multipoint In a point-to-multipoint network, up to
nine WDS APs provide wireless links to
connect up to nine LANs. One AP is
designated as the root (multipoint) AP
connected to a wired infrastructure. The
other APs are called child APs. Child APs
establish a backhaul connection with the
root AP and, at the same time, provide
LAN switching. Omni-Directional antenna— to
which the root AP connects.
Directional antennas— to which
the child APs connect.
Wireless Infrastructure This is an inside/outside wireless
network where one or more WDS APs
are used to establish a wireless backhaul
and connect clients or LAN segments to
the wired LAN. An Omni-Directional or a sectored
antenna.
Determining the Antenna Locations
The following factors determine the locations where you can place the antennas relative to one another
and the distances between them:
•
Type of antennas. The ExtremeWireless antennas are described in Antenna Installation on page 23.
•
Length of cable connecting the antenna to the AP.
•
Data rate required.
•
In a LAN-to-LAN network, the distance between the buildings.
•
Obstructions in the signal path.
•
In a wireless infrastructure network, the area around the antenna where clients need to
communicate with the AP.
Directional and omni-directional antennas are often installed on rooftops. The directional antenna can
also be installed on the side of a building. The following sections describe the factors that affect the
range of these antennas.
Line of Sight
The shape of the radio beam, defined as the Fresnel Zone, is widest in the middle. The Fresnel Zone is
shown as the gray area between the antennas in
Fresnel Zone and Line of Sight Clearance . The exact
shape and width of the Fresnel Zone is determined by the distance between the antenna and frequency
of the radio signal.
The radius of the radio beam, shown as the lower half of the Fresnel Zone, is the distance from the
center of the beam outward in any direction. The length of the radius is not based on the data rate and
the type of antenna.
AP Site Preparation
ExtremeWireless™ External Antenna with Wave 2 8