There is provided a converter for converting a received RF signal into a DC signal for powering a load, the converter comprising: a rectifier arranged to generate, based on the RF signal, the DC signal and one or more harmonics of the RF signal, and to output the DC signal and the one or more harmonics together with a component of the RF signal; a first planar transmission line arranged to guide the received RF signal to the rectifier; and a second planar transmission line arranged to receive from the rectifier the DC signal, the component of the RF signal and the one or more harmonics from the rectifier, and to reflect the one or more harmonics back towards the rectifier. The first planar transmission line is further arranged to reflect back towards the rectifier RF signals from the rectifier that are based on the reflected signals. The converter further comprises a low-pass filter for supplying the DC signal to the load, the low-pass filter comprising an inductor and a third planar transmission line that. connects the second transmission line to the inductor, wherein the third planar transmission line and the inductor are arranged to transmit the DC signal and to substantially block the component of the RF signal and the harmonics of the RF signal.