Rectifier for low power input

I'm going to design a rectifier for low power input at 2.45 GHz.

How low is the limit for input level? The lower, the better.

Now I'm referring to the attached pdf. If I use many diodes, can I get high output voltage?

My desired voltage is around 0.5 V.

If I can get that voltage from the rectifier, it can be boosted with TPS61220.

I have designed a dipole with diode detector/rectifier at 2.45 GHz; it delivered ~0.2 V on a 10 Megaohm load with ~ -10 to 0 dBm.
With 0 to +10 dBm, >0.5V can be expected. HSMS-2825 diodes were used, I tested also Siemens BAR-12 and other Schottky diodes.

The diode was simply mounted in the center of the half-wave dipole.
Schottky detector diodes are typically calibrated as RF detectors at -20 dBm which is the limit power level for a square-root response. Above -20 dBm, Schottky diodes are rather linear. Above 0 dBm, they mostly reflect the incident power.