On 22/08/2019 01:06, Roger Hayter wrote:
Roger Hayter wrote:

John Rumm wrote:

On 21/08/2019 13:16, dennis@home wrote:
https://www.bbc.co.uk/news/business-48859331

Someone really should tell them that the normal RFID tags in use are not
powered by radio waves.

You do know what the RF in RFID stands for don't you?

Radio frequency does not necessarily imply radio (electromagnetic)
waves. In fact, if you have an RF magnetic field generated there will
be some EM radiation around. But I believe if is purely the near field
magnetic induction at RF that excites the tag. I also believe, but my
knowledge is limited, that RF excited tags exist for some purposes, but
are not the common ones. ICBW

Well that was a bit confused. in the last whole sentence I meant of
course that *radio wave* excited tags exist for some purposes where the
reader cannot be close enough to the tag for magnetic excitation.

Ultimately there is sod all difference.

Magnetic, capacitative or RF coupling are all just termns that are used
to ID what mode predominates. At a few feet at GHz frequecies its RF.
You are well into far field






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