Re: 10 GHz oscillator and switch

yep, length does no change the impedance.
check the `frequency pulling` plot of the VCO to see what happens when the output load is not matched, it will give some idea.

How is it possible that the length does not change the impedance? I mean if the phase is shifting (Electrical length) then the absolute value of the impedance should change as well. Where I am doing a mistake here?

Thank you!

Just to give myself a reply :)

The impedance is defined as Zo = sqrt(L/C), if I match the characteristic impedance for my circuit (50 ohm), this will not depend on the length of the line. But it is true that going 'through' the line the impedance changes but at its end will be always 50 ohm.

yep you got it