A PCB-Embedding Scheme for LCP Ribbon Waveguide at D-Band

This paper reports on a D-band polymer waveguide PCB integration concept whereby the waveguide and wave launcher are embedded in the flex layer(s) of a rigid-flex PCB buildup. We here report on the design, fabrication and measurement of a first prototype that launches the CPGENxAAAEx11 mode in a ribbon waveguide using a Vivaldi-type differential structure. Measurements were done using GSG on-wafer probes via an intermediate planar balun. At 140 GHz, the attenuation of two back-to-back launchers with an 8.5 cm section of waveguide was measured to be 10 dB, to which the waveguide itself contributed 2 dB.