User's Manual

3. Pre-Installation Procedures 3-2

Antennas must have a clear view of each other, or “line of sight”. Binoculars may be

used evaluate the path from the desired location of the near antenna to the desired

location of the far antenna. To confirm Line of Sight:

o Ensure that no obstructions are close to the transmitting/receiving path. Take into

consideration trees, bridges, construction of new buildings, unexpected aerial

traffic, window washing units, etc.

o Ensure that each antenna can be mounted in the position required to correctly

align the antenna with its link partner.

The antennas must also have a clear radio line of sight. If a hard object, such as a

mountain ridge or building, is too close to the signal path, it can damage the radio

signal or reduce its strength. This happens even though the obstacle does not

obscure the direct, visual line of sight. The Fresnel zone for a radio beam is an

elliptical area immediately surrounding the visual path. It varies in thickness

depending on the length of the signal path and the frequency of the signal. The

necessary clearance for the Fresnel zone can be calculated, and it must be taken into

account when designing a wireless links.

As shown in the picture above, when a hard object protrudes into the signal path

within the Fresnel zone, knife-edge diffraction can deflect part of the signal and cause

it to reach the receiving antenna slightly later than the direct signal. Since these

deflected signals are out of phase with the direct signal, they can reduce its power or

cancel it out altogether. If trees or other 'soft' objects protrude into the Fresnel zone,

they can attenuate (reduced the strength of) a passing signal. In short, the fact that

you can see a location does not mean that you can establish a quality radio link to

that location. Consult factory for a link planner spreadsheet that calculates the

Fresnel ratio and helps determine link feasibility.

4) Determine Antenna Mounting Locations: Antennas can be mounted on an antenna

mast, brick, masonry or wall.

5) Determine EVENT 5800 Installation Locations: A EVENT 5800 can be installed on a

tabletop or cabinet or rack mount. The site must provide DC power.

6) Document Potential Sources of Co-location Interference: When antennas are located

on a roof or pole with other transmitters and receivers, an interference analysis may

be required to determine and resolve potential interference issues. The interference

analysis needs to be performed by an RF engineer. The specific information required

for each transmitter and receiver includes the following:

o Transmitting and/or receiving frequency

o Type of antenna

o Distance from EVENT 5800 (horizontal and vertical)

o Polarity (horizontal or vertical), if applicable

o Transmit power level