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"Wes Stewart" ha scritto nel messaggio
... 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 |