An electrically conductive coating of an automotive heatable windshield has a
communication window having an enhanced frequency selective surface having arranged
passing areas (uncoated areas) and blocking areas (coated areas) to pass and block,
respectively, predetermined wavelengths of the electromagnetic spectrum. In one
nonlimiting embodiment, the frequency selective surface includes a pattern having
a first plurality of arcuate break lines on one side of a dividing break line and
a second plurality of arcuate break lines on the other side of the dividing break
line. An elongated continuous blocking area is between adjacent break lines. The
arcuate break lines of a group are nested within one another with the arcuate break
line having the largest radius of curvature adjacent the dividing break line. The
break lines each have alternating blocking and passing areas. In another embodiment,
the enhanced frequency selective surface has a plurality columns spaced from one
another by a continuous elongated blocking area. Each of the columns includes passing
areas with each of the passing areas have a perimeter with a blocking area in the
perimeter spaced from the perimeter. The perimeters of the passing areas contact
one another with the blocking area of adjacent passing areas spaced from one another.
The elongated blocking area between the break lines and columns extend to the perimeter
of the communication window. In this manner current passing through the coating,
passes through the communication window to eliminate hot and cold spots around
and within the perimeter of the communication window.
