CTP Systems CTPhone 1900, Applications Manual

Page: 41 / 132

DOC00101-01 2-13
CTPhone 1900 System Planning
Figure 2-10. Signal Attenuation Caused by Range
Obstructions
RF signals are also attenuated by obstructions in their path. Table 2-B
illustrates attenuation caused by common materials in a building.
Although signals can travel through obstacles, you should place base sta-
tions so that signals begin their travel with a clear line of sight and travel
through obstacles afterwards. In the example shown in Figure 2-11, the
base station is placed to maximize line of sight and oriented to provide
greater coverage down the horizontal corridor.
Figure 2-11. Maximizing Line of Sight
Table 2-B. Signal Attenuation Caused by Building Materials
Object
Approximate Loss in
dB
Concrete
with metal siding
Brick
Plaster
Walls with windows
with metal coating
20
30
15
10
10
20
Venetian blinds
open
closed 10
20
Soft partitioning 3 to 4
1 10 100
meter meters meters
-30 dBm
40 dB -50 dBm
60 dB -62 dBm
72 dB -90 dBm
100 dB Power:
Loss:
20
meters 50
meters
-78 dBm
88 dB
corridor
BS1