Adtran TRC4305 Manual Do Utilizador
TRACER 4305 System Manual
Section 2, Microwave Path Engineering Basics
612804305L1A-1A
© 2002 ADTRAN, Inc.
15
where the variables in the equation are defined as
P
R
received power (Watts)
P
T
transmitted power (100 mW (max) for TRACER 4305 - adjustable)
G
T
transmit antenna gain
G
R
receive antenna gain
λ
carrier wavelength (c / ƒ) (meters)
d
path distance (meters)
L
other losses (RF coaxial cable, etc.)
The transmitted power is limited for the 5.8 GHz U-NII band to a maximum of 30 dBm. The actual
transmit and receive antenna gain values are strictly dependent upon the physical characteristics of the
antennas installed for each link. Typical gains are between 20 and 30 dB. For example, a 4 foot diameter,
flat panel C-band antenna from a popular antenna manufacturer advertises a gain of 23.5 dB. The carrier
wavelength is the physical wavelength of the main RF carrier being used for communication, and is
usually approximated at the center frequency of the band, which is 5787.5 MHz. This gives a wavelength
of 5.18 cm.
transmit and receive antenna gain values are strictly dependent upon the physical characteristics of the
antennas installed for each link. Typical gains are between 20 and 30 dB. For example, a 4 foot diameter,
flat panel C-band antenna from a popular antenna manufacturer advertises a gain of 23.5 dB. The carrier
wavelength is the physical wavelength of the main RF carrier being used for communication, and is
usually approximated at the center frequency of the band, which is 5787.5 MHz. This gives a wavelength
of 5.18 cm.
The path distance is simply the physical distance between the transmit and receive antennas. For the
TRACER 4305 these distances can range up to 15 miles. The final parameter L incorporates all other
signal power losses in the microwave link, most of which are caused by antenna feed.
TRACER 4305 these distances can range up to 15 miles. The final parameter L incorporates all other
signal power losses in the microwave link, most of which are caused by antenna feed.
4.
OUTPUT POWER
Transmitted power limitations for the 5.8 GHz U-NII band is governed by the Effective Isotropic Radiated
Power (EIRP) of the system. Per FCC 15.407 rules, the TRACER 4305 is permitted a maximum EIRP of
53 dBm. EIRP can be calculated using the following equation
Power (EIRP) of the system. Per FCC 15.407 rules, the TRACER 4305 is permitted a maximum EIRP of
53 dBm. EIRP can be calculated using the following equation
where P
T
is the transmitted power (in dBm), G
T
is the transmit antenna gain (in dB), and L
F
is the feedline
loss (in dB).
For example, a TRACER 4305 system transmitting at 20 dBm will result in the following restrictions on
antenna gain:
antenna gain:
Since antenna gain is directly affected by antenna size, an EIRP restriction of 53 dBm will limit antenna
selection. However, per FCC rules EIRP is calculated for the total system (transmitter, feedline, and
antenna), and additional antenna gain may be used to compensate for feedline loss. In some cases, adding
additional length to your feedline cable will permit you to select a larger antenna. Refer to Table 3 on page
19 for a listing of coaxial loss for common cable types (per foot).
selection. However, per FCC rules EIRP is calculated for the total system (transmitter, feedline, and
antenna), and additional antenna gain may be used to compensate for feedline loss. In some cases, adding
additional length to your feedline cable will permit you to select a larger antenna. Refer to Table 3 on page
19 for a listing of coaxial loss for common cable types (per foot).
EIRP
P
T
G
T
L
F
–
+
=
(dB)
53dBm
20dBm
G
T
L
F
–
+
≤
(dB)
G
T
L
F
–
33dBi
≤
(dB)