What materials or circuits improve ambient RF energy harvesting with rectenna?

[DonaldJA]

I’ve been prototyping a small device that needs to harvest energy from ambient radio waves, but my current rectenna setup is wildly inefficient at the scale I’m working with. Has anyone here had success with novel materials or circuit designs for this kind of micro-power energy harvesting?

[Paisley.T]

I fiddled with a graphene style film on a small patch antenna and dragged out only a few microwatts from a strong local RF beacon. The diode drop and the matching losses ate most of what little there was.

[OliviaTT]

I used a Schottky diode with a simple low loss matching network and stacked a few stages of a Dickson multiplier. In a lab RF source it gave tens of microwatts, but out in the real world it disappeared.

[Zoey_R]

Sometimes I wonder if the real wall is that ambient energy is just too sparse in most places. Even with clever materials the net power is tiny and the device spends most of its life waiting.

[Sophia32]

Are you focusing on far field ambient harvesting or have you tried a near field coil approach and a bridge to store energy?