Microwave RF Repeaters
use bandpass filters to separate the transmit
and receive signals from the radio terminals
that pass through the repeaters. There are rules
on what frequency spacings are permitted. When
a repeater is detail designed in a radio relay
network, these rules must be understood and followed.
In general, the rules conform to those used by
terminal radios. There are exceptions from time
to time.
The two basic repeater specifications that apply
are the Transmit to Receive (T-R) Spacing and
the Transmit to Transmit (T-T) Spacing (same
as Receive to Receive Spacing). Simple duplex
equipment configurations are easy to understand
as only T-R spacing applies. The more complex
1+1, 2+1, 3+1 and other multiline configurations
demand more study before being able to reach
a rule conclusion. Please see the following diagrams
to understand more about the spacing definitions. |
 |
Table
20, MW RF Repeater - Frequency Spacings |
| RF
Repeater |
Repeater
Bandwidth, MHz |
T-R
Spacing
MHz, min.,
Common Feeder |
T-T
Spacing
MHz, min.
Common Feeder |
| RF-1500E |
16 |
49 |
28 |
| RF-2000E |
20 |
50 |
28 |
| RF-2000EW |
30 |
80 |
42 |
| RF-2500E |
20 |
50 |
28 |
| RF-4000 |
40 |
80 |
80
(with digital radio) |
| RF-4500 |
40 |
80 |
80
(with digital radio) |
| RF-6000E |
30 |
80 |
56 |
| RF-6000EL |
28 |
80 |
56 |
| RF-6000EW |
40 |
100 |
80 |
| RF-7000E |
30 |
80 |
56 |
| RF-7000EL |
28 |
80 |
56 |
| RF-8000E |
30 |
80 |
56 |
| RF-8000EL |
28 |
80 |
56 |
| RF-11000 |
40 |
130 |
80 |
| RF-11000L |
28 |
130 |
80 |
The term Common
Feeder refers to a single coaxial cable or
waveguide used to connect all the signals under
consideration to the microwave antenna. Configurations
where Separate Feeders are used may have closer
system frequency spacings.
Examples:
–
|
Separate
transmit and receive feeders when dual
polarized antennas are used. |
–
|
Separate
transmit and receive antennas, dual polarized
T-R, T-R with adjacent channels on opposite
polarization. |
These Separate Feeder configurations require consulting
with engineering for semi-custom work. The work
is relatively easy but is not in normal documents. |
V = Vertical Polarization. H = Horizontal
Polarization
Channel Pairs: 1, 1' ; 2, 2' ;...6,
6'.
|
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