Abstract: The device comprises a first path provided with an amplifier (1) amplifying in a first frequency band, and a second path provided with an amplifier (2) amplifying in a direction opposite to that of the first amplifier and in a second frequency band other than the first frequency band, a first filter element (L1) having a low pass characteristic for transmitting the signals of the first path, and a second filter element (C1) having a high pass characteristic for transmitting the signals of the second path. The two paths are combined by a third filter element (CA) having a high pass characteristic, arranged in series with a fourth filter element (LA) having a low pass characteristic, whose junction point is connected to ground by a matched impedance (ZCA), and a signal polarity inverting element (TA) is inserted in series between two of the filter elements.

Abstract: An arrangement for supplying current to a wideband transmission cable includes an all-pass circuit having a high-pass path (VPH) and a low-pass path (VPB) in which the signals in the transmission cable are recombined by virtue of the presence of a phase inverter. A current supply supplies current to the transmission cable via a supply point situated in the low-pass path.

Abstract: A multiple coupler which comprises a low-pass path (VPB) and a high-pass path (VPH) and frequency separation elements comprising a capacitive element C and an inductive element L, whose impedances Z.sub.c and Z.sub.l, respectively, satisfy the relation Z.sub.c Z.sub.l =Z.sub.o.sup.2. The low-pass path comprises a phase inverter INV to enable recombination of the signals without any distortion.