Adtran TRC4106 Manual Do Utilizador
Section 2, Microwave Path Engineering Basics
TRACER 4206 System Manual
16
© 2002 ADTRAN, Inc.
612804206L1-1B
5.
PATH LOSS
The expression
where
f
carrier frequency (Hz)
λ
carrier wavelength (c / f) (meters)
d
path distance (meters)
c
speed of light, free-space (meters)
is called the path loss, and increases rapidly as either path length increases or carrier wavelength decreases
(which happens as the carrier frequency increases). So, longer microwave paths will naturally experience
more path loss than shorter paths. Likewise, higher frequency microwave communication will experience
more path loss than lower frequency microwave communication.
(which happens as the carrier frequency increases). So, longer microwave paths will naturally experience
more path loss than shorter paths. Likewise, higher frequency microwave communication will experience
more path loss than lower frequency microwave communication.
Table 2, tabulates path loss values for various path lengths for both 2.4 GHz and 5.8 GHz systems. Values
not listed in the table can be interpolated from those listed.
not listed in the table can be interpolated from those listed.
When using decibel notation, the received power equation becomes
or
Table 2. Path Loss for Given Path Lengths
Path Length
(miles)
Path Loss 2.4 GHz
(dB)
Path Loss 5.8 GHz
(dB)
1
104
112
2
110
118
3
114
121
4
116
124
5
118
126
10
124
132
15
128
135
20
130
138
25
132
140
30
134
141
35
135
143
L
P
4
πd
λ
----------
2
4
πdf
c
------------
2
(dB)
P
R
P
T
G
T
G
R
L
20 · log
10
4
πdf
c
------------
(dBm)
P
R
P
T
G
T
G
R
L
L
P
(dBm)