Normal Incidence on Multiple Dielectric Interfaces

A plane wave is normally incident from air onto a multiple dielectric interface. Although Layer $1$ is $\frac{{}_1}{4}$ thick, the system is not perfectly matched, as seen from the standing$-$wave pattern for One percent of the incident power is reflected.

Standing$-$wave pattern in air

$($a$)$ Determine the standing$-$wave ratio for

$S=1\mathrm{.}22$

$($b$)$ Determine $lo{n}_{r2}.$

$er2=10\mathrm{.}7$