- #1
tomcorker
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In a lab session we were investigating the LC tank circuit of a superhet radio. The tank consisted of a ferrite coil antenna connected in parallel with a variable capacitor. A signal generator was connected to a second ferrite antenna (the drive antenna) and placed close to the first in order to induce a signal.
Now, my lab notes say that the LC tank circuit is at resonance when the voltage out is a maximum and the phase shift relative to the drive antenna is +-90 degrees. I'm fine with the maximum voltage, but why the phase shift? The L and C are parallel so the voltage over them must be common. So the phase shift must be something to do with the coupling between the two antennas? But I've no idea why...
Now, my lab notes say that the LC tank circuit is at resonance when the voltage out is a maximum and the phase shift relative to the drive antenna is +-90 degrees. I'm fine with the maximum voltage, but why the phase shift? The L and C are parallel so the voltage over them must be common. So the phase shift must be something to do with the coupling between the two antennas? But I've no idea why...