N-stage rectifier as AM demodulator?
You might achieve more sensitivity by operating a diode with 1uA or 10uA of bias current. A 1 MegOhm resistor from +9 volts will do this. For reduced capacity, use a small leaded resistor??
You need a R+C load: 100Kohm and 10pF is 1uS time constant, giving you excellent response to your 10uS bit times.
Your ZERO RF output will be +9v * 100,000/1,000,000 = 0.9 volts.
You can drop the Grounded resister (the 100,000) to 10K if you want.
The primary load on the RF input, given the diode is biased ON, will be the 10pF capacitor.
Given 1pF = -J 159 ohms at 1GHz, the 10pF will be -j 16 ohms, a heavy load on an antenna. You might use just a few picoFarads, then into 10Kohm series into 100pF shunt, into opamp buffer. This light load should give 5X larger rectified voltage.
Given the diode is biased ON, a fast diode should handle the 900MHz.
Given 0dBm across 50 ohms is 0.632 volts PP, and -20 dBm is 0.0632 volts PP, and -40dBm is 0.00632 volt PP (a mere 6 milliVolts), you have interesting possibilities here.
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To recover the OOK/AM modulation, you need to remove the RF (1.1 nanosecond period) yet preserve the 10uS bit times.
A 3_component cascade: 220,000 ohm to +1v, into the diode anode, with the cathode to a 10,000 ohm resistor (in parallel with 100 pFcap to remove the 900MHz), should do this.
GIven 100pF has only 1.6 ohms reactance, compared to the 10,000 ohm resistor, the RF will be well suppressed limited by your Ground Plane and your lead inductance.