Estimating RF Coverage
6-12
InterReach Unison Installation, Operation, and Reference Manual
CONFIDENTIAL
D-620003-0-20 Rev J
6.2
Estimating RF Coverage
The maximum power per carrier (based on the number and type of RF carriers that
are being transmitted) and the minimum acceptable received power at the wireless
device (i.e., RSSI, the design goal) establish the RF link budget, and consequently the
maximum acceptable path loss between the antenna and the wireless device.
Figure 6-1
Determining Path Loss between the Antenna and the Wireless Device
(P - L
coax
+ G) – RSSI = PL
(1)
The path loss (PL) is the loss in decibels (dB) between the antenna and the wireless
device. The distance, d, from the antenna corresponding to this path loss can be calcu-
lated using the path loss equations in Section 6.2.1 and in Section 6.2.2.
Coaxial cable is used to connect the RAU to an antenna. The following table lists
coaxial cable loss for various cable lengths.
Table 6-10
Coaxial Cable Losses (
L
coax)
Length of Cable
(.195 in. diameter)
Loss at
800 MHz
(dB)
Loss at
1900 MHz
(dB)
0.9 m (3 ft)
0.6
0.8
1.8 m (6 ft)
1.0
1.5
3.0 m (10 ft)
1.5
2.3
RAU
P = power per
Distance = d
Antenna Gain = G
RSSI = power at the
wireless device
carrier from the RAU
Coax cable loss =
L
coax
