Substrate Integrated Bragg Waveguide: a New Transmission-Line Medium for Millimeter-Wave and Terahertz Systems Integration

We demonstrate an air-core single-mode hollow waveguide that uses a Bragg reflector structures in place of the vertical metal walls of the standard rectangular waveguide or via holes of the so-called substrate integrated waveguide. The high-order modes in the waveguide are substantially suppressed by a modal-filtering effect, making the waveguide operate in the fundamental mode over more than one octave. Numerical simulations show that the propagation loss of the proposed waveguide can be lower than that of classic hollow metallic rectangular waveguides at terahertz frequencies, benefiting from a significant reduction in Ohmic loss. To facilitate fabrication and characterization, a proof-of-concept 20 to 45 GHz waveguide is demonstrated, which verifies the properties and advantages of the proposed waveguide. A zero group-velocity dispersion point is observed at near the middle of the operating band. This work offers a step towards a new transmission-line medium that can be integrated within a substrate, either in integrated circuit or multi-chip module technology, for broadband millimeter-wave and terahertz applications.