Broadband Sub-THz Dielectric Waveguides Characterization

In this paper, several plastic fiber for high-speed mmW communications are measured in the sub-THz range using waveguide transitions specifically designed for its characterization. These waveguide transitions have the advantage of being low cost and very broadband. First, rectangular to circular waveguide transitions are introduced. Then circular to plastic waveguide transitions are presented. These transitions are designed and measured at D-band (110-170 GHz) and H-band (220- 330 GHz). Next, the characterization of plastic waveguides of different shapes and in both frequency bands is carried out. Within the two considered bands, the proposed transitions achieve both simulated and measured insertion losses (IL) as low as 1 ±0.2 dB and 2 dB, respectively. For the plastic fibers, a good agreement between theoretical model and experimental results are obtained with loss per meter varying between 4 and 20 dB/m depending on the fiber geometry and operating frequency.