Oh wow, if the RF receiver stage design is completely passive, it's extremely easy to build, even for complete beginners. Now all we need is an smartphone RFID

Oh wow, if the RF receiver stage design is completely passive, it's extremely easy to build, even for complete beginners. Now all we need is an smartphone RFID app to decode the waveform, and you could have a really sneaky RFID sniffer disguised as a smartphone + some weird thing inserted inside the headphone jack :) I wonder how well this completely passive RF receiver stage works. Also, would it be possible to build a passive emitter ? Then you could have a complete RFID transceiver connected to an audiojack. Again, plugged in a smartphone, this would be a pretty mobile tool.