I have a question which seems like an easy one, but I couldn't find anything on Internet to be 100% sure.
The free space path loss equation is:
Now, if the receiving antenna is at the same height as the transmitting antenna, $d$ is just the horizontal distance between the two. But if we now move the receiving antenna up and down (without increasing $d$), the straight line between the two antennas is this:
and the path loss equation becomes:
is this correct? Maths seems to agree, but I don't know if I am not missing somthing obvious here. Thanks.