Coupling a plurality of transmitters operating with different carrier frequencies to a single aerial is often effected by multiplexing the output signals by means of band-pass filters in the output frequency band. The band-pass filters have one end connected to a start network and from there to the aerial via an aerial transmission line, and the other end to the transmitters via circulators. For an optimal use of the available frequency band, for making less stringent requirements on the band-pass filters and for providing a dynamic channel assignment feature, the transmitter coupler according to the invention has a first stage in the form of a digital coupler and a second stage in which multiplexing is effected, using band-pass filters. The transmitter output signals are combined in the digital coupler, in the pre-group phase, by digital signal processing, preferably using the GTFM method. In the second stage the output signals of the parallel-arranged digital coupler are subjected to a digital-to-analog conversion in the group-phase and to frequency conversion. |