Passive RFID through objects

Question

I wanted to build a device to track the stuff I have in my bag. I wanted to use passive RFID tags which I would place on my objects.

The problem now is that I don't have much experience with RFID and I am not sure how well certain tags can be detected. I've researched a bit and found out that UHF tags are very good for tracking multiple things, but also that they don't penetrate materials as good as lower frequency chips. Do you think a 850 - 960 MHz chip would be readable if it is placed inside a thick book like a novel?

Answer 1

UHF will theoretically work. The factors that could decrease reading performance are:

1. The material and thickness of the bag (metal or metallic insertions like aluminium foil will definitely not work).
2. The number of tags in the bag and their positions (if two or more UHF tags are pressed one to each other one or all of them will not be read). The more the tags the more the chance for two of them interfering.
3. The material to which they are fixed (dielectric materials such as liquids, metals will dramatically decrease performance)
4. Reading distance, tag and reader performance.
5. Interference by dielectric materials between reader antenna and tag (if a human body is placed between tag and antenna or tag is very close to human body - 2 cm - the reading distance will decrease)

The answer to your last question is Yes in about 99.99999% of the time with a controlled environment.

Answer 2

If it is near the top cover , then the dielectric of the rest of the book acts as half capacitor e=2.3 dielectric ground plane while the top increases the surface as a radiator. But it is also shifting downward the antenna tuning to reflect more energy back inside.

So it will still work but may affect sensitivity.