It appears that nearly all "passive RFID" tag-reader combinations have around a 5-10cm specification for reading distance.
But I am interested in approx. 20 cm reading distance.
I am assuming one of these is the right approach to follow, but I'm not sure which:
Perhaps the 5-10 cm range is a constraint of the passive RFID technology itself, and I should look into other technologies?
Or is it that there exist variants within the passive RFID technology (and the frequency band within which they operate)?
Or should I look into different kinds of tags specifically (I highly doubt this is the case since they do after all transmit upon being energized by the reader)?
Or should I consider adding a specific external antenna to my RFID reader?
Note: I am aware of "Active RFID", but given its battery requirement on the tags, this is not ideal for my experiment.