A wireless power transmitter comprising: a transmitter coil (106, 210, Ls) for coupling oscillating electromagnetic energy to a receiver coil of a receiver device ; first (L3sa, 450) and second (L3sb, 452) balanced inductors coupled to the transmitter coil (106, 210, Ls) and configured to be driven by a respective first and second oscillating current, wherein the first (L3sa, 450) and second (L3sb, 452) balanced inductors comprise respective first and second magnetic cores; a switching inverter or amplifier for driving the first (L3sa, 450) and second (L3sb, 452) balanced inductors and the transmitter coil (106, 210, Ls); and a layer of magnetic material separating the respective first and second magnetic cores of the first (L3sa, 450) and the second (L3sb, 452) balanced inductors; wherein the first (L3sa, 450) and second (L3sb, 452) balanced inductors share the layer of magnetic material such that the layer of magnetic material in combination with the first (L3sa, 450) and second (L3sb, 452) balanced inductors determine respective inductances of first (L3sa, 450) and second balanced inductors (L3sb, 452) during operation of the wireless power transmitter, wherein the first (L3sa, 450) and second (L3b, 452) balanced inductors and the switching inverter or amplifier are configured such that, when each of the first (L3sa, 450) and second (L3sb, 452) balanced inductors is driven with its respective oscillating current, magnetic flux generated in the layer of magnetic material by the first inductor (L3sa, 450) is substantially cancelled by magnetic flux generated in the layer of magnetic material by the second inductor (L3sb, 452). a transmitter coil (106, 210, Ls) for coupling oscillating electromagnetic energy to a receiver coil of a receiver device ; first (L3sa, 450) and second (L3sb, 452) balanced inductors coupled to the transmitter coil (106, 210, Ls) and configured to be driven by a respective first and second oscillating current, wherein the first (L3sa, 450) and second (L3sb, 452) balanced inductors comprise respective first and second magnetic cores; a switching inverter or amplifier for driving the first (L3sa, 450) and second (L3sb, 452) balanced inductors and the transmitter coil (106, 210, Ls); and a layer of magnetic material separating the respective first and second magnetic cores of the first (L3sa, 450) and the second (L3sb, 452) balanced inductors; wherein the first (L3sa, 450) and second (L3sb, 452) balanced inductors share the layer of magnetic material such that the layer of magnetic material in combination with the first (L3sa, 450) and second (L3sb, 452) balanced inductors determine respective inductances of first (L3sa, 450) and second balanced inductors (L3sb, 452) during operation of the wireless power transmitter, wherein the first (L3sa, 450) and second (L3b, 452) balanced inductors and the switching inverter or amplifier are configured such that, when each of the first (L3sa, 450) and second (L3sb, 452) balanced inductors is driven with its respective oscillating current, magnetic flux generated in the layer of magnetic material by the first inductor (L3sa, 450) is substantially cancelled by magnetic flux generated in the layer of magnetic material by the second inductor (L3sb, 452). <EOS>