Termination resistors in Ethernet in Kilo-Ohms instead of Ohms?
For example, using a twisted pair, the formula that determines characteristic impedance, Z0 is: -

\$Z_0 = \dfrac{120}{\sqrt{\epsilon_r}}\cdot ln(\dfrac{2S}{D})
\$



If permittivity (\$\epsilon_r\$) is held constant at 4 then you will find that you have to get a a very large "S" distance before the impedance is in the kohm range.

For D = 0.5mm, an S value of 8 mm is still only 208 ohms. An S value of 1000 mm yields an impedance of 498 ohms. A 10m gap is still only 636 ohms.

Try this for your self here

If you don't terminate cables in their correct characteristic impedance you'll get reflections, standing waves, nulls, over-voltage, data errors etc..