How RFID Tags Work: Detailed Explanation for Physics Students

[Opus_723]

I'm afraid my Google-fu is failing me. Try as I might, I can only find very basic descriptions online of how RFID tags (specifically passive ones) work. I'd like to actually know what the microcontroller in the tag does, and how it creates a signal the reader can pick up and decode. For example, many articles I've found say that the integrated circuit sends a signal by modulating the impedance of the tag antenna, but I'm interested in how it does so.

I'm a physics student, not an electrical engineer, so I would ideally like to see an explanation that is quite detailed, but hopefully keeps the jargon to a minimum. If someone could point me in the right direction, I'd really appreciate it!

 

[UsableThought]

I'm a physics student, not an electrical engineer, so I would ideally like to see an explanation that is quite detailed, but hopefully keeps the jargon to a minimum. If someone could point me in the right direction, I'd really appreciate it!

I know nothing about RFID, but I can suggest how you might learn more. Since you're unlikely to find explanations written for physics students as such, you can pretend temporarily that you're interested in electronics; and since you are researching a system built of electronics products, rather than Google you might go straight to some highly relevant sites and browse within those sites - specifically, to web sites for companies which make such products & therefore have an interest in providing product info to first-time buyers/builders.

Electronics part makers typically provide various levels of explanation for their products, from high-level overviews ("What is a Q10Wabba Widget?" all the way down to "data sheets" that explain "typical applications" in quite some detail ("Here are some typical circuits for a Q10Wabba Widget"); somewhere in between you may find the sort of mid-level explanations you seek. So if you haven't already you might visit some manufacturing sites & poke around, e.g here is a company called IMPINJ that makes some variant called RAIN RFID; here's one of their overviews - https://www.impinj.com/about-rfid/how-does-rfid-work/ - and in the horizontal menu above the overview there are links to other high-level topics. Poke about and you'll surely find more fine-grained information directly related to products & applications.

You can also go a slightly more indirect route: Start with a distributor (e.g. Mouser or DigiKey); search for RFID, - e.g. http://www.mouser.com/Search/Refine.aspx?Keyword=rfid - and from there drill down to various products; such products will have data sheets and links to manufacturers; so you can find more manufacturer sites that way. It does take a bit of work, but is sometimes useful.

Also, now that I think about it, electrical engineering journals online will typically have white papers on this or that technology; I'm surprised Google wouldn't give you such hits straight away.

 

[berkeman]

I'm afraid my Google-fu is failing me. Try as I might, I can only find very basic descriptions online of how RFID tags (specifically passive ones) work.

The Wikipedia article looks to have lots of good information. Have you already read through it and read some of the links at the end?

https://en.wikipedia.org/wiki/Radio-frequency_identification