My project partner and I are working on making a rf-dc energy harvesting circuit capable of lighting an LED (even intermittently) or trickle charging a coin cell battery over a long time. We are looking to use 2.4Ghz and 5 Ghz wifi bands to convert as much energy as possible using a Cockcroft-Walton voltage multiplier. I know that distance will be extremely low but we are more interested in showing it is possible than it being useful as of now. As many stages as necessary to power the led briefly, I think the minimum stages is 4-5. I have a dual band antenna 50 ohm impedance, schottky diodes, ceramic caps(various sizes), and access to a network analyzer to build a matching circuit. Supposing -20dbm or better is this possible?
How do I calculate the necessary capacitor sizes to use for the multiplier and the size of a load capacitor for instance to charge the battery? What is a good source for pcb for surface mounting that is better than fr-4?