User Manual

Section 2, Microwave Path Engineering Basics TRACER 4206 System Manual
16 © 2002 ADTRAN, Inc. 612804206L1-1A
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.
Table 2 on page 16, tabulates path loss values for various path lengths for the TRACER 4206 system.
Values 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
(dB)
1 112
2 118
3 121
4 124
5 126
10 132
15 135
20 138
25 140
30 141
35 143
L
P
4πd
λ
----------


2
4πdf
c
------------


2
==
(dB)
P
R
P
T
G
T
G
R
L– 20 · log
10
–++
4πdf
c
------------


=
(dBm)
P
R
P
T
G
T
G
R
L– L
P
–++=
(dBm)