Air-filled waveguides to cut losses in mass-market radar

AT&S has demonstrated a way of integrating microwave chips and waveguides into low-cost PCBs with the help of research performed by Imec on system systems integration. This approach will make it easier to produce low-cost automotive radar modules operating in the 100GHz-plus D-band as well as millimeter-wave 6G communications interfaces.

The favored approach to implementing waveguides has been to move to air-filled waveguides inserted into the PCB substrate. The use of fully metalized sidewalls in these waveguides offers significantly reduced signal loss compared to the substrate-integrated waveguides (SIWs) that use rows of vias and the planar interconnect technology currently used in radar systems. But the air-filled waveguides have proven to be significantly more difficult and expensive to form. The design developed by AT&S and Imec provides a way to build these waveguides in a cheaper way, offering a five-fold reduction in losses compared to existing mass-market techniques.

In the technology demonstrated at International Microwave Symposium this week (June 12), the waveguides have solid copper sidewalls that can be integrated into a multi-layer PCB. The cavities can be arbitrarily shaped, the company claimed. With only conductor losses being significant, the new achieves a loss of 0.07 to 0.08dB/mm across the 115 to 155 GHz frequency range, translating. AT&S expects to be able obtain further improvements in losses over the coming years.

“Imec’s 140 GHz radar chips and packaging design expertise have given us a significant head start. We believe that our new packaging approach can be utilized to create efficient, compact, and high-resolution 140 GHz radar modules for automotive applications, creating vehicles that are increasingly ‘aware’ of what is happening, both in-cabin and around them,” said Erich Schlaffer, program manager for R&D at AT&S.