Power ratio
Impedance matching
-
consider a system of two parallel interfaces, from left to right the medium impedances are respectively
,
and
. The distance between the two interfaces to be
-
by the continuity equations of the displacement and velocity at the two interfaces, we conclude the total reflective coefficient of the double layer system to be
-
we define the effective impedance to be
, thus acquiring a similar reflective coefficient as for a single interface system with
and
Quarter wave matching (i.e. the interface spacing with impedance
has length
)
- Satisfied under the condition
,
- this gives the zero reflection condition for quarter wave matching
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