The filter combiner can combine the output of up
to eight transmitters. In order to use nine to sixteen transmitters
in a cell, two filter combiners and two antennas must be used. It
is a narrow band combiner where the frequency of each of the
connected transmitters (TRXs) must be tuned by adjusting a
filter. This is done automatically by the system but nevertheless
takes some time.
The total loss in a filter combiner is around 3-4 dB.
The combiner output is connected to the transmitting antenna on
top of the cabinet via a Measuring Coupling Unit (MCU) and a
bandpass filter TXBP.
The transmitter divider (TXD) distributes the loopback signal
from the MCU to the different transmitters to enable automatic
tuning of the filters in the combiner. It also enables Voltage-
Standing-Wave Ratio measurements (VSWR).