Comment by vel0city
Glass is a resistor, it is not conductive. Its actually a pretty good resistor, its often used to separate extremely high voltages. Those little discs you often see holding high-voltage power lines are often made from glass.
Silicon is not a conductive metal. Its a semi-conductor, it needs doping to become a good conductor. That's why its used in IC's. Naturally not very conductive but react a little with something else and suddenly it becomes a pretty good conductor. Make a mask of the channels where you want that conductivity, and suddenly you can draw little wires.
Also why this system needs to be customized and tweeked to work with each specific panel of building glass it is placed with to get the full RF signal pass through