rfid backscattering

Hey guys,

I'm doing the project of kind of sensor which might employ the wireless stuff, currently I dont really get the idea of backscattering, why and how we discuss about that? How to regulate the input dc level of RFID seems to be really interesting question, how do you guys solve this problem? Can anyone provide the paper or reading material about that?

I get a RFID book call "Design and Optimizaion of passive UHF RFID systems", which is really good in explaining the idea. Recomm that......

Thanks in advance.

backscatter means that the same signal that
is send by the reader is reflected back by the antenna(tag)
modulated by modulating the reflection coeficient.
Or in other words the reflected signal contains the
information that the tag is sending.
The tag does that by changing the impedance of its
own antenna.

The DC value is the tag acting has a harvest device.
It collects the energy sent by the reader and convert it
to a DC value as if were a power supply.

You also can find usefull information in book call "RFID Handbook. 2end edition" by K. Finkenzeller (translated by R. Waddington).