RFID Backscatter level detection and code inquiry

Thanks for reading. I am trying to determine if I need a specific reader/write RFID module to be able to detect the levels of backscatter between the reader and the RFID tag. I am trying to use the levels of backscatter to determine how different objects act as a shield for RF signals. I also am quite new to arduino platform, so perhaps a more senior maker could lend some advice. As far as I understand, I need an Xbee com card and then the reader/writer, and tags. If anyone has input I would greatly appreciate it!

Thanks.

I have been designing RFID stuff for years but never come across the term back scatter. What do you mean?
You do not get any signal strength indication from an RFID reader.

I'm basically looking for a way to detect signal strength from the RFID tag. Perhaps this helps:

http://reeves.ee.washington.edu/people/faculty/nikitin_pavel/papers/APmag_2006.pdf

This is what I am looking to do: http://web.mit.edu/rahul_b/www/Fluid_Level.pdf

Thanks again.

Thanks for the links. Interesting reading but these refer to UHF RFID. That is not the normal sort of RFID reader and these tend to be very expensive in the several hundred dollar region. Normal RFID works either in the 125KHz region by disturbing an inductively coupled field or in the 13MHz region using the power in the transmission to power a tiny transmitter transmitting back at 3.25MHz.
On the other hand UHF RFID tags can work at a longer range and can read multiple tags in the same field. However, their cost is prohibitive to most hobbyists.

Thanks for the info and quick reply. I am building this system for my business, so a $200-$300 investment isn't a big deal, considering the amount I've already put into the project. Do you know of any UHF RFID reader/writer modules that can interface with an Arduino mega that will provide signal strength back to the microprocessor? The primary function of my system relies on detecting signal strength, so I need to be sure that I can collect that data from the module. Your help is much appreciated.

I don't but this one will let you set thetransmitter power level. You could do that to see what tags respond. With a successive approximation approach you can get eight bits of resoloution.