A power combiner for coupling, splitting, or coupling and splitting high-frequency signals, the power combiner has a first input for a first high-frequency signal, a second input for a second high-frequency signal, an output, an equalizing connection, a first electrical conductor arranged between the first input and the output, wherein the first electrical conductor has a first total surface shaped primarily as a first planar surface electrode, a second electrical conductor arranged between the second input and the equalizing connection, wherein the second electrical conductor has a second total surface shaped primarily as a second planar surface electrode, and wherein the second electrical conductor is capacitively and inductively coupled to the first electrical conductor; and a cooling body, wherein more than 70% of the first total surface of the first electrical conductor is a same distance from the cooling body as the second total surface of the second electrical conductor.