ADTRAN TRACER 6000 SERIES, Руководство пользователя

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Section 2 Microwave Path Engineering Basics TRACER 6000 Series Split System Manual
20 Copyright © 2005 ADTRAN, Inc. 612806320L1-1B
connector on the coaxial cable be weatherproofed to prevent corrosion and electrical shorting.
Table 3 gives typical loss figures for some of the more common coaxial cable types (per 100 feet or
30.5 meters).
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)
In areas where lightning strikes are frequent, a lightning arrestor should be installed
directly on the antenna coaxial cable. Installing lightning arrestors helps protect the
RF electronics (including the TRACER 6320 unit) in the downstream path from
damaging voltages and currents.
IF lightning arrestors must have the ability to pass DC voltages (up to ± 60 volts)
and should be installed with care.
Table 3. Typical Coaxial Loss for Common Cable Types
Cable Type 5.8 GHz Loss/100 ft (in dB)
RG58 N/A
RG8 (air) N/A
RG8 (foam) N/A
1/4” Coax 11.36
3/8” Coax 9.65
1/2” Coax 6.49
5/8” Coax 4.90
7/8” Coax N/A
1 1/4” Coax N/A
1 5/8” Coax N/A
5.8 GHz Elliptical Waveguide 1.23
L
P
4
π
d
λ
----------
⎝ ⎠
⎛ ⎞
2
4
π
df
c
------------
⎝ ⎠
⎛ ⎞
2
= =
(dB)