Wi Lan Inc EB03 Manuale Utente

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Appendix A: Planning Your Wireless Link
124
 AWE 120-24 Installation & Configuration Guide
Antenna Installation Factors
Some factors you should consider when installing antennas into your wireless system are listed below.
Factor
Description
Maximizing the 
AWE 120-24’s 
Capabilities
• Minimize obstructions in the radio path
• Line Of Sight (LOS) is crucial for reliability
• Ensure that equipment is installed correctly
• Ensure proper grounding, testing, and alignment of antennas
• Install in environmental conditions that are suitable for the  AWE  unit
• Select proper antennas and cable for the application
• Ensure sufficient gain for the intended application
Safety
• Proper grounding of antenna apparatus in accordance with respective 
Electrical Code(s) is crucial
• Wi-LAN recommends using a surge arrestor where the antenna cable 
enters the building
• All installations should be completed by a qualified and competent RF 
technicial
EIRP
• Effective Isotropically Radiated Power (EIRP)
• EIRP is the amount of power that is transmitted to the air from the 
antenna
• EIRP levels depend on the power of the radio transmitter, the size of the 
antenna, and the losses incurred in the antenna cable
• To remain license-exempt the EIRP must remain under 4 W or 36 dBm in 
Canada and the United States for point-to-multipoint applications. In 
Europe, this value is reduced to 100 mW or 20 dBm.
Note: EIRP = Power out of unit – Power lost in cable + Gain in power from 
Antenna
Fade Margin
See 
LOS
• Line of Sight (LOS)
• LOS is a football shaped pattern known as the Fresnel Zone, which must 
be kept clear of obstructions. See 
, page 117 for more 
information
• Visual line of sight must be achieved. When standing at the antenna 
position, you must be able to see the remote antenna