Can you please provide some information about read ranges?
There are many different types of RFID systems used in the United States, and they all have different read ranges. Passive low-frequency (LF) and high-frequency (HF) transponders have a read range of up to 3 feet. Conventional passive ultrahigh-frequency (UHF) systems typically have a range of about 20 to 30 feet. However, larger tags can be read from a distance of as much as 100 feet away. And with phased array antenna systems, it is possible to read a passive tag from up to 500 feet away, though you would need to have a device to send energy to the tag within 20 or 30 feet. Active systems use a battery to broadcast a signal and have a much longer read range. Typically, an active tag can be read from about 1,000 to 1,500 feet away.
—Mark Roberti, Founder and Editor, RFID Journal
How Can I Embed Tags in Metal? »