Capacitance of plane, sqrt(L/C) or 1/(jωC)

[alextang0112]

Hey guys,

I know that the characteristic impedance of a transmission line can be written as Z0 = sqrt(L/C)

But the impedance of a capacitor can also be written as Z = 1/(jωC)

If it is sqrt(L/C), then impedance is inversely proportional to sqrt(C); if it is 1/(jωC), then the impedance is inversely proportional to C

Why are they different ?

Thank you.

 

[FvM]

Both "impedances" are completely different properties. You have reactance of the capacitor, an imaginary quantity and the real characteristic impedance of the transmission line. L and C in the transmission line impedance formula are specific quatities (per length unit).