Physically, the force-wave reflection coefficient seen at port of a series adaptor is due to an impedance step from , that of the port interface, to a new impedance consisting of the series combination of all other port impedances meeting at the junction. Let
Let's check this ``physical'' derivation against the formal definition Eq. (F.28) leading to in Eq. (F.30). Define the total junction impedance as
This is the series combination of all impedances connected to the junction. Then by Eq. (F.32), for all . From Eq. (F.23), the velocity reflection coefficient is given by
the result follows.