[Moved]Wireless Power Transfer and Maximum Rectifier Efficiency

I've been reading on wireless power transmission and some academic publications show systems with greater than 50% efficiency with single diode rectifiers (half wave, voltage driven class E). If only for half of the cycle the diode conducts, how is this possible. Is something with the inductive resonant coupling causing the waveform at the input of the rectifier not to be purely sinusoidal? Anyone have any clue what is happening?

There's no reason a half wave rectifier can't (in principle) have nearly equal efficiency to a full wave rectifier. It just changes the distortion in the coil currents a bit.

Perhaps the paper was referring to 50% efficiency of AC power transfer, without DC rectification included.
Generally WPT circuits use at the receiver side an AC/DC converter, or a diode bridge rectifier followed by a DC/DC converter.