Robert Baer wrote:
"So the only real performance variable left is the holes in the
conductive surface."

A plane window, like the fuselage itself, acts as apipe below cutoff
frequency. Minimum size for low attenuation is 1/2-wavelength.

The thicker the window frame, the longer the waveguide and the greater
the attenuation at frequencies below cutoff. See page 277 of
"Transmission Lines, Antennas, and Wave Guides" by King, Mimno, and Wing
to quantify the attenuation. It`s big below cutoff.

Best regards, Richard Harrison, KB5WZI