A converter for converting a received radio frequency, RF, signal into a DC signal for powering a load, the converter comprising: a first rectifying arm for generating a DC signal based on a first RF voltage input obtained from the received RF signal, and a second rectifying arm for generating a DC signal based on a second RF voltage input obtained from the received RF signal, wherein the received RF signal provides a voltage difference between the first RF voltage input and the second RF voltage input, and each rectifying arm comprises: a rectifier (220a,220b) arranged to generate, based on its RF voltage input, the DC signal and one or more harmonics of its RF voltage input, and to output the DC signal and the one or more harmonics together with a component of its RF voltage input; a first planar transmission line (210a, 210b) arranged to guide its RF voltage input to the rectifier; and a second planar transmission (230a, 230b) line arranged to receive from the rectifier the DC signal, the component of its RF voltage input and the one or more harmonics from the rectifier, and to reflect the one or more harmonics back towards the rectifier; wherein the first planar transmission line (210a, 210b) is further arranged to reflect back towards the rectifier radio frequency signals from the rectifier that are based on the reflected signals; and wherein the first planar transmission line of the first rectifying arm is connected to the first planar transmission line of the second rectifying arm by a connection which comprises an inductor to allow DC current to flow between the first rectifier arm and the second rectifier arm. a first rectifying arm for generating a DC signal based on a first RF voltage input obtained from the received RF signal, and a second rectifying arm for generating a DC signal based on a second RF voltage input obtained from the received RF signal, wherein the received RF signal provides a voltage difference between the first RF voltage input and the second RF voltage input, and each rectifying arm comprises: a rectifier (220a,220b) arranged to generate, based on its RF voltage input, the DC signal and one or more harmonics of its RF voltage input, and to output the DC signal and the one or more harmonics together with a component of its RF voltage input; a first planar transmission line (210a, 210b) arranged to guide its RF voltage input to the rectifier; and a second planar transmission (230a, 230b) line arranged to receive from the rectifier the DC signal, the component of its RF voltage input and the one or more harmonics from the rectifier, and to reflect the one or more harmonics back towards the rectifier; wherein the first planar transmission line (210a, 210b) is further arranged to reflect back towards the rectifier radio frequency signals from the rectifier that a rectifier (220a,220b) arranged to generate, based on its RF voltage input, the DC signal and one or more harmonics of its RF voltage input, and to output the DC signal and the one or more harmonics together with a component of its RF voltage input; a first planar transmission line (210a, 210b) arranged to guide its RF voltage input to the rectifier; and a second planar transmission (230a, 230b) line arranged to receive from the rectifier the DC signal, the component of its RF voltage input and the one or more harmonics from the rectifier, and to reflect the one or more harmonics back towards the rectifier; wherein the first planar transmission line (210a, 210b) is further arranged to reflect back towards the rectifier radio frequency signals from the rectifier that are based on the reflected signals; and