Option 1 – Separate feeders for each antenna
The easiest option for running a Triband Site is separate feeders for each antenna. This allows the individual control signals to be sent to the Tower Mounted
Amplifiers (TMA’s) over their own feeders.
The disadvantage with individual feeders is that depending on the length and type of feeder cable, the operator may end up paying 30% more than using a combining system.
Option 2 – Combining with Triplexers
Combining triband sites with triplexers can be significantly cheaper than running individual feeders.
The problem occurs when the operator wishes to use current 1800 TMA technology with a 12V supply and current sensing alarms, and the Ericsson ASC TMA using a 48V supply with proprietary digital control.
The configuration above uses triplexers with DC Bypass on the 2100 port for the ASC supply and control signal. The 1800 supply and control signals are extracted by DC inserters at the BTS end, and run via separate DC cable to the top of the mast, where they are inserted back into the system via more DC inserters.
It could be argued that a better way to do this is using triplexers with DC Bypass on the 1800 port and running separate cables for the ASC unit, as the digital control signal is less affected by long cable runs.
If there is a separate control signal output from the BTS, the bottom DC Inserters may not be required.
