Window panes have been an obstacle to good mobile reception but these new panes, which will first be introduced from the end of 2018 on the new fleet of Desiro High-Capacity trains for Rhine-Ruhr-Express in Germany, are expected to provide a 33% increase in 4G signal.
Window coatings currently in use improve thermal efficiency and reduce penetration of solar radiation but limit mobile reception. The coating developed by Siemens is frequency-selective and therefore solves this problem.
An electrically-conductive, transparent layer made from metals or metal oxides is applied to the window panes. Along lines in a special structure, lasers are used to vaporise the pane's metallic coating. This allows radio signals in certain frequency ranges to pass through unhindered, while radio signals with other frequencies are attenuated.
Measurements conducted with a modified Austrian Federal Railways (ÖBB) Railjet have shown that the time window in which good 4G reception is available increases by 33%.
"We wanted a cost-effective solution for our customers," says Mehrdad Madjdi, from the Siemens Mobility. "The window panes can be used for decades without the need for maintenance. They may be more expensive to buy, but they generate significant savings in the long term compared with in-train repeaters."
Siemens says another advantage lies in the fact that the window panes will meet future mobility standards as well, meaning the latest mobile services are available to passengers immediately without the need for any further investment. Installation is also cost effective because no additional technical components are needed and technicians do not require special qualifications.