help me this concept: impedance mismatch at low f

Hi,

I am confused at this concept:
for characteristic impedance is only dependent on TL geometry, not f. let's say if I have 2 different TL with 50, 100ohm. do they will have reflection at low f (~1MHz)? from math, Γ=(Z2-Z1)/(Z2+z1), It seems it always has reflection. but we know at low f, we never need to care about reflection.
pls correct my concept.
thx!

You will get a change of impedance, but since the lengths of the traces are so short compared to a wavelength, the impedance seen at one end of the line will be very close to the impedance loading the other end.

just to add to the reply of flatulent that the concept of mismatch still valid also at low freq. also at DC.

Just consider the concept of "mismatch" as "how far from the maximum power transert".

It's well know that to transfer the maximum power you must close over complex conjugate, In DC (and low Freq) means Rsource=Rload