For instance, has there been any experimentation with using metal-dielectric composite materials for insulating the antennas?
I have not seen any advances in Near Field Communication (NFC) transponders that would allow tags to be read even when stacked one on top of another. I do not think insulating the antennas would work, as the issue is one antenna blocking energy from reaching the one below it. Insulation would only help to mitigate the effects of detuning when two antennas touch.
SATO Global Solutions acquired a company called Magellan Technology in 2013. Magellan had developed a technique called phased jitter modulation (PJM), which enabled HF tags to be read, even when tags were stacked one on top of another. I don't think anyone is producing NFC transponders with PJM technology. If any of our readers are aware of either NFC transponders that use PJM or some other innovation that would enable tags to be read when closely stacked, they are invited to post information below.
—Mark Roberti, Founder and Editor, RFID Journal
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