How to make a DIY radio density meter?
I have some experience with arduino and netduino, soldering, some super basic electronics, but I have no clue where to start with a radio density meter. What kind of signal do I have to generate? What kind of chip/circuit will I need to read the radio signal and analyze it?
I'm mainly interested in search terms, web sites, books, etc that will point me in the right direction - but any help at all is appreciated.