Waveguides: AT&S Develops Next Generation of Mobile Communications

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What comes after 5G? The Austrian technology company makes an important contribution to the development of tomorrow’s mobile communication and radar technologies and is already working on 6G. 

AT&S has been addressing the next generation of mobile communications for some time. “We have been thinking about what will come after 5G for quite a while“, says Erich Schlaffer, AT&S Project Leader and Programme Manager for High Frequency and High Speed at AT&S. “Waveguides will be part of it.” Waveguides are hollow metal structures which conduct electromagnetic signals with virtually no loss. AT&S can integrate waveguides for data transmission at very high frequencies directly into printed circuit boards.

Modern communication infrastructure has to deal with a steadily growing flood of data. The increasing demand for bandwidth has, among other things, led to the use of ever higher frequencies in mobile communications. Although they have a lower range, they can transport significantly more data. The 5G networks which are currently being built will use substantially higher frequencies in metropolitan areas than the infrastructure of preceding generations.

As a result, the requirements for the radio cells which will build such networks are also increasing. As the technology leader, AT&S has developed printed circuit boards which enable the transmission of high-frequency signals between antennas and signal processing chips with virtually no losses. For 5G communication, for example, this is achieved through air cavities, which are integrated into the printed circuit board and massively reduce the losses of high-frequency signals.

The generation after next

However, if frequencies continue to increase, even these approaches will reach their limits at some point. This is why AT&S is already developing processes to enable the efficient transmission of signals with a much higher frequency. Waveguides are hollow metal tubes whose cross-section is tuned exactly to the frequency of a signal. The higher the frequencies become, the lower the dimensions of the waveguides. This allows integration in printed circuit boards or substrates. 

With the help of waveguides, signals in the range from 70 to 140 gigahertz and beyond can be transmitted back and forth without losses between antennas and signal processing chips. In comparison, the high-frequency signals in the coming 5G network range between 26 and 39 gigahertz. To manufacture waveguides, AT&S removes part of the material in the desired shape from a layer of the printed circuit board, plates it with metal and closes the channel with a cover that is also metallic. The construction has to be very accurate, stable and tight to ensure that signal transmission also works across several centimetres on the printed circuit board. The cover used is thinner than human hair.

Self-driving cars

In addition to their application in the generation after next of mobile communication networks, waveguides are also interesting for radar sensors in the automotive industry. Autonomous vehicles and driver assistance systems rely on high-resolution radar sensors in order to capture their surroundings in the greatest detail possible. Images of such detail are only possible with the corresponding high-frequency signals and high bandwidth.