I'm trying to figure something out and so far no one has come up with an answer.

If I have a voltage divider network (Just 2 resistors) and I bypass the bottom one with a cap with an AC source in. How do I figure out the impedance?

My goal is the following: put a sine wave in with say 4v p-p in @1kHz, have an R1 and R2 (equal value) with a bypass cap on R2 (the other side of R2 is connected to ground) and say I get 1v p-p out (the middle of R1 and R2 is my output). I want to take that circuit and replace it with just R1 and R2 (keeping R1 the same value) and get the same amplitude out. I don't care about phase right now.

Anyone have any ideas?