A communications satellite has several radiating elements connected respectively to the output ports of a hybrid matrix power amplifier the input ports of which are connected to respective output ports of a low level beam forming network. The low level beam forming network has input ports to which are applied individual beam signals and these are combined within the network to provide at the network output ports different component sums of the input signals. By selecting appropriate connections between the beam forming network and the hybrid matrix power amplifier on the one hand and between the hybrid matrix power amplifier and the radiating elements on the other hand, desired beam overlap and equal power amplifier loading can be achieved.