Can an active 2.4 GHz tag be interrogated underwater (salt water and sweetwater) by an RFID reader located above the surface?
I know of no deployments in which active tags have been used underwater, and I have not seen any tests conducted on the use of active RFID in such a scenario, so I am unable to provide the distance at which active tags can be read.
I believe the reason few deployments have been carried out with active tags underwater is that active RFID systems suffer from the same issue as passive ultrahigh-frequency (UHF) technology: Water absorbs electromagnetic energy in this frequency range. In fact, microwave ovens use 2.4 GHz to heat up food. So I would guess that the read range would be very short—a couple of feet—if you could interrogate the tag at all under such conditions.
—Mark Roberti, Founder and Editor, RFID Journal
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