Structure design and electroplating fabrication of cost-effective externally copper-coated polypropylene dielectric hollow waveguide for low-loss, flexible and robust delivery of terahertz waves

There is an urgent demand for low-loss, flexible, robust, and cost-effective waveguides to support terahertz (THz) 6G wired communications, sensing, and imaging applications. An external copper (Cu)-coated polypropylene (PP) THz hollow waveguide (HWG) structure was proposed based on theoretical analysis of the finite element method. Low theoretical transmission losses at 0.1 and 0.3 THz were achieved by optimizing the waveguide structural parameters, including inner diameter and wall thickness, etc. An electroplating apparatus was built up to prepare the dense and smooth Cu reflective layer on the outside of the PP tubes. The transmission losses of the Cu/PP HWG sample at 0.1 THz and 0.3 THz were 1.83 dB/m and 1.18 dB/m, respectively. The waveguide sample exhibited robust transmission behaviors (output power fluctuation below 3.7 %) in −78.5/65 °C environments and after 10 cycles of anti-vibration test (10–500 Hz). This study provided a different insight into developing low-loss, flexible, durable, and low-cost metal/dielectric THz HWG, which would be valuable for establishing reliable THz wave transmission systems in practical engineering applications.