9018-18076.pdf.pdf - 第28页
4-4 Site Preparation 4 RF Attenuation Requirements Ta b l e 4 - 6 Determining Available Site Attenuation with a site al lowance or a differen t wal l attenuation Parameter Val ue R; Required Site Attenuation (dB) n; Numb…
RF Attenuation Requirements 4
Site Preparation 4-3
Calculating Site Attenuation
To obtain the necessary attenuation at the installation site you can increase the distance between the
equipment and the property boundary or you can add walls or other attenuating structures:
• Required Site Attenuation (R)
R = Target Site Attenuation – Site Allowance
Where:
• Target Site Attenuation = 15 dB
• Site Allowance for your site = ____________
• The distance from the equipment to the property boundary (D) can be calculated as follows:
D = 30 or 30*log
-1
((R – n * W)/20) whichever is greater.
Where:
• R = Required Site Attenuation
• n = Number of concrete walls between equipment and property boundary.
• W= Attenuation of the wall (a concrete wall without openings has an attenuation of 10 dB)
• Additional attenuation (X) due to a D greater than 30 meters.
X = 20log(D/30)
Where:
• D = distance from equipment to property boundary.
• Total attenuation (A) is calculated as follows:
A = X + n * W
Where:
• X = Additional Attenuation
• n = Number of concrete walls between equipment and property boundary.
• W= Attenuation of the wall (a concrete wall without openings has an attenuation of 10 dB)
Figure 4-3 Determining Available Site Attenuation
4-4 Site Preparation
4 RF Attenuation Requirements
Table 4-6 Determining Available Site Attenuation with a site allowance or a different wall
attenuation
Parameter Value
R; Required Site Attenuation (dB)
n; Number of Walls
W; Attenuation per wall
R – n *W ; Remaining Attenuation Requirement (dB)
D; Distance from Equipment to Real Estate Border (m)
