Re: What is Transponder?
Rayengine, be carefull with RFID the tag is often refered to as the transponder. In this case the IC is normally a two terminal device where the terminals go out to a printed antenna with a cap & resistor to form a resonant circuit.
When RF is applied, by an interegating transmitter the tag rectifys the voltage produced in the formed resonant circuit & self-powers itself. It then backscatters it's ID to the interegator by shorting the antenna terminal out. If this is what you want then buy a tag, there is no need to buy the IC.
The interegating tranmitter normally has a transponder stage in it, or what is often called this because the section of the circuit is transmitting & receiving from the same antenna at the same time, a constant RF transmission is required else the tag will power down, yet at the same time the interegator must receive the data from the tag.
This is passive technology, it's a bit different with active. whether what you want to do is possible depends on the frequency band & technology you use, it will be a lot harder to get 100cm when a tag is implanted, antenna efficiency drops very low.