SIW 90-degree twist for substrate integrated circuits and systems

A 90-degree twist based on Substrate Integrated Waveguide (SIW) and using LEGO-like interconnected PCB building blocks is proposed for the first time. The fabrication involves a low-cost standard PCB process and a connection of building blocks similar to assembling LEGO toys, which have been enjoyed by millions of children. The validation of the proposed process consists of a 90-degree twist operating over the Ka-band (from 26.5 to 40 GHz). The fabricated component achieves a return loss of less than -18 dB and an insertion loss of better than 1 dB over the Ka-band. The proposed 3-dimensionnal geometry represents one of the key components for future microwave and millimeter-wave System on Substrate (SoS). It allows an efficient interconnect between horizontal and vertical SIW PCBs. As an application example, a wideband dual-polarized end-fire antenna operating from 32 to 38 GHz is demonstrated based on the proposed 90-degree twist. It achieves an isolation of higher than 32 dB, a return loss of better than -18 dB and a gain higher than 14 dBi at 35 GHz.