Vertically Stacked Double-Layer Substrate-Integrated Non-Radiative Dielectric Waveguides for THz Applications

Non-radiative dielectric (NRD) waveguides were developed to address the discontinuity-caused leakage problem of dielectric waveguides. With the proliferation of substrate-integrated circuits, planarized substrate-integrated NRD (SINRD) waveguides have emerged, which are found more suitable for terahertz (THz) integrated systems. However, in the making of SINRD waveguides, a process-related conflict may arise between the air-hole perforation of a hosting substrate and its essential residual metallic coating on the perforated region. It is found through this work that the conflict can be solved by using a multi-layer topology. The difference in drilled air hole entry and exit can be reduced. Moreover, the exposed metallic coating over both sides of the double-layer SINRD waveguide can be well preserved. Therefore, a dense air-hole perforation is allowed when needed. In this paper, this vertically stacked guiding structure is presented and studied and experimentally verified, which demonstrates the interesting features of this technique.