what input impedance do i need

This may look like a basic homework problem, but I am just learning... I have a lossless transmission line (characteristic impedance = 70 Ohm, 1.5 cm long) connected to a load of 50 Ohm. How do I calculate the input impedance of this combination? I think Zin should be dependent on the RF frequency due to the impedance mismatch; something looks like:

but I need a formula for it. Where may I find some instructional material online which I can follow to calculate the input impedance for my setup? Thank you very much.

Hi

try Google.......transmission line input impedance

you will find plenty...like Wikipedia

regards

Zin = Zo (ZL + Zo tan (βl))/(Zo+Zl tan(βl))

how is it? can you get the answer?

Hi

You have already been given the formula to compute this impedance by dhavalelectron...

regards,

Thank you dhavalelectron! I also found the formula in Wikipedia following tyassin's instruction. Thank you everyone!