Richard Clark wrote,

My EM guys, Physics types, [from my working days] indicated that the
three dielectric interfaces, adhesive to glass to adhesive, all with
different dielectric coefficients create reflections at the boundaries.

Hi Dave,

Poor theory. Reflection is not loss. There are reflections galore on
a radiator that supports the Standing Wave and yet with a large enough
metal surface it is nearly 100% radiative.

As for this boundaries explanation, those "Physics types" clearly did
not have any working knowledge (experience) - about as useful as
Cecil's poorly offered Light analogies suffering from the same lack.
I further note that none of this indicts clear glass (which may have
been a semantic issue) to the tune of nearly 1dB.

73's
Richard Clark, KB7QHC


Hi Richard,
absent any numbers on the loss tangent of automobile window
glass at the frequency in question, any estimate of loss is just a guess.
73,
Tom Donaly, KA6RUH