How does the following circuit works?
That circuit is overly complicated, and thus, burns most of the energy input in losses from the much too many unneeded components.

The following is the much simpler circuit of a crystal radio, which makes you hear AM radio from the nearby station, without a battery.







simulate this circuit &ndash; Schematic created using CircuitLab

It's so well-known it even was on Hal Roach’s Rascals and a gimmick in some comic magazine

Well, how does this work? Energy is taken from the EM field, rectified/demodulated by the low drop, soft I/U characteristic, hence Germanium, diode, then fed into the high-ohms earphones. Coil and capacitator are only there for selection of a specific station. When you leave them out, you hear AM-Babble.

And that's what your circuit does. It leaves out the frequency selection, feeding all received energy to the consuming circuit on the right. The capacitators and diodes indeed work as a voltage doubler, but that's nonsense because they have so much loss you are better without them.