This paper presents an analysis for the impedance transformation ratio of microwave rectifier, implemented as an energy recycling unit suitable for RF outphasing transmitters. The experimental demonstration is realised by two single-ended microwave rectifiers with different impedance transformation ratios to separately replace the power-wasting resistive load of an isolating combiner in a multilevel LINC system. The measurement results show that the implemented rectifier can improve the overall efficiency of the multilevel LINC system from original 39.5 % to 46.7 % and 44.9 % respectively, without affecting linearity.

This paper presents the concept and measurements of a new microwave rectifier based on the time reversal duality of power amplifiers. It is shown that the proposed rectifier can simultaneously provide high efficiency at large input power range over much more improved bandwidth compared to the conventional rectifier from time reversal duality. It is also reported that the proposed rectifier allows reconfiguration of the efficiency at input power range without placing the tunable elements. A 10 W wideband power amplifier with 79%drain efficiency at 1.85 GHz is used to validate the concept. By making the gate bias network short-terminated and replacing the drain termination with the DC load resistor for power amplifier, the circuit can operate as microwave rectifier with taking part of bandwidth from power amplifier. Measurements show the efficiency bandwidth with larger than 70 % rectifying efficiency at 15 dB input power range over a 1.7–1.95 GHz frequency range. The measurements thereby validate the presented concept and demonstrate the potential of the proposed rectifier for use in future wireless energy harvesting applications.