Installation Manual

Tsunami MP.11a Antenna Installation Guide
Clearance Factor
For optimal performance of your outdoor wireless link, the signal path between the Base Station Unit and
Subscriber Unit must provide sufficient clearance.
Note: A outdoor wireless link that lacks sufficient clearance will suffer from poor performance, which is
typically perceived as slow network response times. Although your Tsunami MP.11a equipment
automatically retransmits every lost data frame due to an out-of-range situation or frame collision, the
larger the number of retransmissions, the lower the throughput efficiency of your wireless link.
This section explains how to determine the clearance that applies in your environment and (if applicable) the
effect of insufficient clearance on the range of your outdoor wireless link.
In “Chapter 1. Preparing for Installation” on page 8, we described the shape of the antenna beam as being
“bulged” in the middle.
Figure 5. Fresnel Zone
If any significant part of this bulged zone is obstructed, a portion of the radio energy is lost, which can affect
the performance of your wireless link in terms of maximum range and transmit rate.
In Figure 5, you see two variables that determine the shape of the antenna beam, also referred to as Fresnel
Zone:
▪ The distance between the antennas (a)
▪ The clearance required for optimal performance (b), where clearance should be interpreted as:
º Vertical clearance above the ground and the highest buildings or objects in the signal path
º Horizontal clearance from neighboring buildings and objects in the signal path.
For optimal range and throughput performance, you must ensure that your antenna installation provides
maximum clearance in both horizontal and vertical direction.
Chapter 2. Determining Range and Clearance 18
CPN 65756 Issue Date: 01 August 2003