This paper discusses ambient RF backscattering and energy harvesting and provides the theoretical and measured results of a 1.8 GHz backscatter and energy harvester. The backscatter is implemented by using a varactor and HEMT transistor for their variable impedance and the rectifier uses a differential topology to optimize RF to DC conversion efficiency. The novel backscatter method achieves a low EVM and can easily be used to achieve a variety of modulations.