Hello Dennis,
Please provide more details to understand your question.
What do you mean with NFC Rx?
What is the external device you would like to communicate with?
I believe you are referring to taking energy from the NFC Field. The amount of power that can be consumed from the field depends on several factors, such as the field strength itself, the coupling coefficient between the Reader and Target antennas and the form factor of the antennas as well as the corresponding matching/tuning circuits. So because of these variants I would like to understand your question better.
Regards!
Jorge Gonzalez
