What metamaterial designs could improve my RF energy harvesting rectenna?

[Frank11]

I’ve been prototyping a small device that needs to harvest ambient RF energy, but my current rectenna setup is terribly inefficient at the low power levels I’m working with. I’m wondering if anyone has practical experience with newer metamaterial designs for this.

[Avery.W]

I tried a metamaterial inspired resonator for a rectenna at 2.4 GHz, but the extra structure just added loss and the gain was tiny. Ambient RF is so weak that diode noise and impedance mismatch still rule the results.

[Scarlett.W]

I spent weeks swapping diodes, substrates, and matching networks. The best I got was a tiny bump in DC output when the input happened to match, but overall efficiency stayed in the 0.01% to 0.1% range at best.

[Emily_G]

Do you think the real bottleneck is the RF power density in the target band, or could a clever resonator design really push the numbers up? It's hard to tell from a few lab demos.

[Jerry.L]

Sometimes I find myself veering into energy storage talk instead of harvesting; even if you grab micro-watts, you then have to store it, schedule a duty cycle, or you’ll never run anything.