funkee wrote:Hey Allen, thanks for the great info about reception. The small rear coupe windows have a film on the exterior with dots as well. Do those help aid in radio reception?
Sorry for the hi-jack...
As mentioned, the "dot matrix" (a subtle throw-back to 80's printers) has nothing to do with reception or the actual glass, it's there to do little more than look pretty and annoy tint installers.
The issue with back glass that contain integrated RF antennas is that metalized window film creates a short between the antenna element and the rear-window defroster. The short shunts the RF energy you are trying to get to your radio to ground instead- this is what caused your radio stations to disappear when you tint your windows; the signal can't get to the receiver in the radio.
The two (antenna and defroster) look very similar but the antenna is at the very top of the glass and the defroster elements are lower- The antenna on our cars is actually all within the "dots" at the top of the glass. You can tell the difference in the two if you follow the "lines" of the wires in the glass since. You will notice there are two separate sets of "wires" in the glass that are not connected to each other.
By taking a razor and cutting the film along the "dot matrix" you physically break the electrical connection between the antenna and the defroster. It doesn't take much but it is important to get all the way to the edge of the glass to the edges of the window which it is usually difficult to reach (if they did a good job installing the tint). Even a small piece still connected (not cut) at the edge of the window will provide an electrical path and cause a short.
Slicing the tint shouldn't create a problem with it sticking and if it is done in the "dots" it isn't noticeable unless you know exactly where to look.
Some tint shops will sell some lesser quality (non-metalized) films to keep reception, sacrificing the heat rejection properties of metalized films. Others may "up-sell" folks on using a vinyl strip over the antenna element- while this solves the problem it accomplishes the same as slicing the tint by electrically isolating the antenna and will often be sold at a higher priced "option" that doesn't look right. I never understood this since it just makes more work for the installer unless they just don't understand the root cause of the reception problem.
/r
Allen