11-06-2013, 10:27 PM
My post #48 crossed with post #47 by boiss: it appears that a supplementary comment is now necessary.
When we have an L/C cct., operating at resonance, which is electro-magnetically coupled to another impedance, the behaviour of that L/C cct. will become modified depending on the nature of that coupled impedance and the degree of coupling it has to that L/C cct. The effect of that impedance on the L/C cct. is called the 'reflected impedance'. That impedance could be reactive or resistive: if it is another L/C cct. and if it is also at resonance, it will reflect a resistance into the original L/C cct. that acts as a parallel resistance with the dynamic resistance of that original L/C cct, thus reducing its effective dynamic resistance and, consequently, the resultant Q. That is why, under those circumstances, the supply current to the original L/C cct. increases as the coupling is increased: energy is being transferred from the L/C cct. to the new, additional L/C cct.
Should the new L/C cct. have a resonant freq. that is slightly different to that of the original L/C cct., we obtain the traditional band-pass tuning response curve: two resonant peaks, the separation of which depends on several factors, the degree of coupling between them being the most significant.
Al. / June 12, 2013 //
When we have an L/C cct., operating at resonance, which is electro-magnetically coupled to another impedance, the behaviour of that L/C cct. will become modified depending on the nature of that coupled impedance and the degree of coupling it has to that L/C cct. The effect of that impedance on the L/C cct. is called the 'reflected impedance'. That impedance could be reactive or resistive: if it is another L/C cct. and if it is also at resonance, it will reflect a resistance into the original L/C cct. that acts as a parallel resistance with the dynamic resistance of that original L/C cct, thus reducing its effective dynamic resistance and, consequently, the resultant Q. That is why, under those circumstances, the supply current to the original L/C cct. increases as the coupling is increased: energy is being transferred from the L/C cct. to the new, additional L/C cct.
Should the new L/C cct. have a resonant freq. that is slightly different to that of the original L/C cct., we obtain the traditional band-pass tuning response curve: two resonant peaks, the separation of which depends on several factors, the degree of coupling between them being the most significant.
Al. / June 12, 2013 //
