Extremely Low-Loss Planar Transition From Hollow Dielectric Waveguide to Printed Circuit Board for Millimeter-Wave Interconnect

An extremely low-loss and high-speed millimeter-wave (mm-wave) interconnect based on hollow dielectric waveguide (HDW) is demonstrated. Though HDW is renowned for its distinguishably low-loss transmission among all dielectric-based competitors, it is criticized for the difficulty of smooth power transition from HDW to planar backplane systems. This article presents a novel approach for planar transition from tubular HDW to printed circuit board (PCB). The proposed transition circuit is composed of a dipole-antenna-like power coupler, a matching metal adapter, and a tapered horn. The experimental result shows only 0.68-dB transition loss at 58 GHz, which is the best value compared to other approaches in the literature. In addition, thorough analysis and modeling for the proposed technique are obtained. It implies the opportunity to apply this approach for applications in higher frequency by scaling. The 16 quadrature amplitude modulation (16QAM) communication over the proposed 1-m interconnect is demonstrated with a maximum data rate of 34 Gb/s. This technique provides an extremely low-loss and structurally stable solution for HDW-based interconnect and transition, which is expected to be applied for 5G/6G high-throughput communication in the near future.