can you have negative inductance?
I have 2 commentaires to reply:
1.- "A negative inductance can be thought
as a capacitance."
It's not true in all cases, only for one frequency (as says one of precedent posts), since magnitude negative or positive capacitance (assuming negative capacitante in theoretical point of view) varies inversely with frequence as |1/(wC)|
and inductance varies proportionally as |wL|.
2.- "As you see from the very different answers, your question isn't clear."
It's clear I think. See my post (5 May 2008 14:14 Re: what does negative inductance mean?), please:
"a pure imaginary characteristic impedance can not transport the energy. (In a classical filter theory is named "The pass band theorem"). However if the sign of both reactances in transmission line is the same, Zo is real.
A more complicated case is when there is a line-loss
Zo = sqrt((R+jwL)/(G+jwC)) = sqrt(Z/Y)
since a propagation constant is Gamma = sqrt(Z*Y) = sqrt((R+jwL)*(G+jwC)) -> exp(Gamma*x) = I1/I2
gives you complex current ratio, you can deduce if the wave is attenuated or ""amplificated"" in function of transmission line-length "x" for all cases of impedace signs and also if has no physical construction."
In addition to this (maintaining theoretical interest), one may be attempted to imagine a real-characteristic impedance transmission line with both negative Inductance and capacitante unit per length:
Zo = sqrt((-L)/(-C)) where Zo is real
But this implies inverting direction of wave propagation or "phase advance" or changing "x" direction, this is derived by the Telegrapher's equations.
Finally, about impedance compensation there a some tecniques based on passive circuits (not all are active circuits), for example that are used in an old crystal filter synthesis for remove parallel capacitance (see the attached image).
Best regards.