A Flexible Non-Radiative Dielectric Waveguide with a 1-dB Loss PCB-to-NRD Coupler for mm-Wave Array Applications

Signal distribution across a large aperture remains a major problem for millimeter-wave (mm-wave) arrays. This paper demonstrates a mm-wave non-radiative dielectric (NRD) waveguide that realizes flexible interconnect and low propagation loss. Two back-to-back grounded coplanar waveguides (CPW-G) are used for coupling from the printed circuit board (PCB) to the NRD waveguide as a forward-wave coupler. Due to the field distribution similarity of the longitudinal section electric (LSE) mode of the NRD waveguide to the quasi-TEM mode of the CPW-G, the proposed coupler achieves a smooth and efficient transition. Measurement results for PCB-NRD-PCB links at 60 GHz with 10-cm and 20-cm lengths are demonstrated. The measured propagation and coupling losses of the proposed NRD waveguide and coupler are 30.0 $\bf \pm$3.3 dB/m and 1.0 $\bf \pm$0.4 dB from 56 to 64 GHz, respectively.