"Wes Stewart" ha scritto nel messaggio
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On 10 Feb 2004 10:07:45 -0800, (Tom Bruhns) wrote:
|I think Wes has given you a nice explanation about _how_, but I'm
|curious _why_ you want to know the Q of an antenna. (Beware...some
|antennas behave as multiple coupled resonators, and it can be
|misleading to try to assign a Q to a whole system of coupled
|resonators. It makes some theoretical sense, at least, if it behaves
|as a single resonator over the frequency of interest, though.)
I'm working for an RFID project (13.56 MHz) and the Q factor is very
important.
We are in the near field and we use the inductive coupling; the Q has to be
between 40 and 60. For Q too high there is not enough bandwidth for the
modulation and the antenna is too much sensible to the environment, for Q
too short the signal is weak.
Massimo