Alvarion BREEZENET RB-DS.11 - Manual (Page 22)

BreezeNET DS.11 Series User Manual
2-6
Path Loss
Path loss is determined mainly by several factors:
♦ Distance Between Sites: Path loss is lower and system performance is better
when distances between sites are shorter.
♦ Clearance: Path loss is minimized when there is a clear line of sight. The
number, location, size, and makeup of obstacles determine their contribution
to path loss.
♦ Antenna Height: Path loss is lower when antennas are positioned higher.
Antenna height is the distance from the imaginary line connecting the
antennas at the two sites to ground level. Ground level in an open area is the
actual ground. In dense urban areas, ground level is the average height of the
buildings between the antenna sites.
Rooftop Installation
Rooftop installations offer several advantages:
♦ Fewer obstacles in the path.
♦ Improved performance due to greater height.
Antennas for Outdoor Applications
The BreezeNET DS.11 series can be used in point-to-point or point-to-multipoint
configurations.
Point-to-Point
The BU-DS.11/RB-DS.11 can be equipped with a directional antenna. The
required antenna gain depends on the required range and performance.
Point-to-Multipoint
Setting up a point-to-multipoint link requires the use of a Base Unit equipped with
an omni-directional antenna (or an antenna with sufficient bandwidth to
illuminate all units) and at least two remote units equipped with high-gain
directional antennas.
Antenna Polarization
Antenna polarization must be the same at both ends of the link. In most
applications, the preferred orientation is vertical polarization, which is better for
above ground propagation. To verify antenna polarization, refer to the assembly
instructions supplied with the antenna set.