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Section 2 Microwave Path Engineering Basics TRACER 6000 Series Integrated System Manual
22 Copyright © 2005 ADTRAN, Inc. 612806420L1-1F
Path Loss (L
P
)
Path loss is the estimated attenuation between the transmit and receive antennas caused by signal
separation and scattering. The path loss is considered basic transmission loss over the microwave link. The
following expression calculates path loss:
where
f carrier frequency (Hz)
λ carrier wavelength (c / f) (meters)
d path distance (meters)
c speed of light, free-space (meters)
or
where d is expressed in miles and f in GHz.
Path loss, as shown here, increases rapidly as either the path length increases or the carrier wavelength
decreases (which happens as the carrier frequency increases). Therefore, longer microwave paths naturally
experience more path loss than shorter paths. Likewise, higher frequency microwave communication
experiences more path loss than lower frequency microwave communication.
The path loss values for various path lengths for the TRACER 64x0 2.4 and 5.8 GHz systems are listed in
Table 7 (miles) and Table 8 on page 23 (kilometers).Values not listed in the tables can be interpolated from
those listed.
Table 7. Path Loss for Given Path Lengths (miles)
Path Length
(miles)
Path Loss (dB)
at 2.4 GHz
Path Loss (dB)
at 5.8 GHz
1104112
2110118
3114121
4116124
5118126
10 124 132
15 128 135
20 130 138
25 132 140
30 134 141
35 135 143
L
P
20 log
4πd
λ
----------
⎝⎠
⎛⎞
⋅=
(dB)
L
P
96.6 20 log
10
d() 20·log+
10
f()
⋅
+=
(dB)