Passive tags and energy driven from RFID reader.

Hello,


Passive tags: Since they don't have battery to power up themselves, they relies on the reader. The electromagnetic waves from the reader induce current on the antenna's tag and so tag powers up the circuitary and broadcasts its message.Reader emits the electro-magnetic waves continuously.

Now my question is : How much energy is extracted by the tag from the reader?

Will the tag recieve and use the entire energy emitted by the reader?
On what factors, energy absorbing is dependent?
If the tag absorbs some part of energy, what happens to the rest of the energy? Is it getting wasted?
Any filtering mechanism is used? Or the tag uses all the emitted energy from the reader?

Are the readers/tags designed to operate in specific frequency range? Suppose, reader/tag designed for UHF range has to be used in UHF only and not in other range. Is it true?

Please throw some light and guide me. Suggest me the suitable artciles emphasizing the above.


-shaikss

You possibly want to visit the edaboard RFID technology group RFID Technologies - Forum for Electronics