A wireless system comprising: an antenna; a plurality of power amplifiers (101, 102, 103, 104; 401, 402), each power amplifier having an input and an output; a plurality of first transmission lines (403, 404, 405), wherein the output of each of the plurality of power amplifiers is electrically coupled to a first end of a different one or more of the first transmission lines, and wherein a second end of each of the first transmission lines is coupled to ground; a central conductive region, the central conductive region having a node coupled to an antenna terminal, wherein the antenna terminal is coupled to the antenna; and a plurality of second transmission lines (111, 112, 113, 114), wherein each of the second transmission lines is coupled to a different output of the plurality of power amplifiers through respective first transmission lines, wherein each of the second transmission lines includes a single transmission line having an open end and an end electrically coupled to the central conductive region, wherein each power amplifier receives an input signal (S1, S2, S3, S4; S) and produces an output signal, and wherein the output signals of the plurality of power amplifiers are magnetically coupled from the first transmission lines to the second transmission lines and added at the node of the central conductive region, wherein each power amplifier comprises a first power amplifier having a first differential output and a second power amplifier having a second differential output, wherein a first output of the first differential output is electrically coupled to a first one of the first transmission lines configured in parallel with one of the second transmission lines, wherein a first output of the second differential output is electrically coupled to a second one of the first transmission lines configured in parallel with said one of the second transmission lines, characterised in a second output of the first differential output being coupled to a first end of a third transmission line, and wherein a second output of the second differential output being coupled to a second end of the third transmission line, the third transmission line having a first portion configured in parallel with a first side of said one of the second transmission lines and a second portion configured in parallel with a second side, opposite the first side, of said one of the second transmission lines. an antenna; a plurality of power amplifiers (101, 102, 103, 104; 401, 402), each power amplifier having an input and an output; a plurality of first transmission lines (403, 404, 405), wherein the output of each of the plurality of power amplifiers is electrically coupled to a first end of a different one or more of the first transmission lines, and wherein a second end of each of the first transmission lines is coupled to ground; a central conductive region, the central conductive region having a node coupled to an antenna terminal, wherein the antenna terminal is coupled to the antenna; and a plurality of second transmission lines (111, 112, 113, 114), wherein each of the second transmission lines is coupled to a different output of the plurality of power amplifiers through respective first transmission lines, wherein each of the second transmission lines includes a single transmission line having an open end and an end electrically coupled to the central conductive region, wherein each power amplifier receives an input signal (S1, S2, S3, S4; S) and produces an output signal, and wherein the output signals of the plurality of power amplifiers are magnetically coupled from the first transmission lines to the second transmission lines and added at the node of the central conductive region, wherein each power amplifier comprises a first power amplifier having a first differential output and a second power amplifier having a second differential output, wherein a first output of the first differential output is electrically coupled to a first one of the first transmission lines configured in parallel with one of the second transmission lines, wherein a first output of the second differential output is electrically coupled to a second one of the first transmission lines configured in parallel with said one of the second transmission lines, characterised in a second output of the first differential output being coupled to a first end of a third transmission line, and wherein a second output of the second differential output being coupled to a second end of the third transmission line, the third transmission line having a first portion configured in parallel with a first side of said one of the second transmission lines and a second portion configured in parallel with a second side, opposite the first side, of said one of the second transmission lines.