Hybrid Metallo-Dielectric Waveguide Architecture for Compact Low-Loss THz Applications

A hybrid metallo-dielectric waveguide (HMDW) architecture is studied and applied to the reduction of transition sizes over discontinuities, in turn the overall dimension of circuits and systems. The scheme is made of mixed dielectric waveguide (DW) and nonradiative dielectric (NRD) waveguide, which are, respectively, deployed for the design of specific building parts in consideration of respective transmission properties of the two waveguides. NRD waveguide with metallic covers is used over discontinuities, which allows for suppressing potential radiation and leakage effects, whereas DW is adopted along discontinuity-free segments to maintain a minimum transmission loss. A back-to-back guiding structure with four 90 $^{\circ}$ bends covered by metal layers is demonstrated and experimentally validated in WR3-band. The simulated and measured insertion losses are comparable to their straight counterpart. With the NRD, the bend radius can be reduced by a factor of about 10, which enables the development of an extremely compact DW terahertz (THz) system. The presented metallized-via-free HMDW can be implemented in high-density integrated low-loss circuits and systems, which is critical in THz manufacturing process.