12-06-2013, 08:17 AM
From an article:
""I have to confess a marked objection to the various statements sometimes seen that the reactances "cancel out". The reactances are not sentient beings! Coils and capacitors do not sit and conspire together to reduce their reactances to zero as the resonant frequency is approached! The reactances within each of the components are still very much present at resonance as is the relative phase difference due to them (if you were to take the components out of the circuit and measure their individual reactances at that same frequency you would see it) but the net phase difference across the input terminals becomes zero because phase differences, unlike reactances, do cancel and all the generator sees is a pure resistance. Hence the conjugate impedance required of the generator to get the most power into the load is also a pure resistance. As we saw in the paragraph above, a reactive load must be driven by a reactive generator having a conjugate impedance, and a vital consequence of the maximum power theorem is therefore demonstrated by tuned circuits themselves""
Full article below:
http://home.freeuk.net/dunckx/wireless/m...ower1.html
Lawrence.
""I have to confess a marked objection to the various statements sometimes seen that the reactances "cancel out". The reactances are not sentient beings! Coils and capacitors do not sit and conspire together to reduce their reactances to zero as the resonant frequency is approached! The reactances within each of the components are still very much present at resonance as is the relative phase difference due to them (if you were to take the components out of the circuit and measure their individual reactances at that same frequency you would see it) but the net phase difference across the input terminals becomes zero because phase differences, unlike reactances, do cancel and all the generator sees is a pure resistance. Hence the conjugate impedance required of the generator to get the most power into the load is also a pure resistance. As we saw in the paragraph above, a reactive load must be driven by a reactive generator having a conjugate impedance, and a vital consequence of the maximum power theorem is therefore demonstrated by tuned circuits themselves""
Full article below:
http://home.freeuk.net/dunckx/wireless/m...ower1.html
Lawrence.
