Substrate Integrated Bragg Waveguide: an Octave-bandwidth Single-mode Functional Transmission-Line for Millimeter-Wave and Terahertz Applications

TL;DR

This paper introduces a novel substrate integrated Bragg waveguide that achieves octave-bandwidth single-mode operation with lower loss than traditional waveguides, suitable for millimeter-wave and terahertz applications.

Contribution

The work presents a new waveguide design using Bragg reflectors for single-mode, broadband operation with reduced loss, verified through simulations and a 20-45 GHz prototype.

Findings

Single-mode operation over more than one octave

Lower propagation loss compared to traditional waveguides

Zero group-velocity dispersion point near the middle of the band

Abstract

We demonstrate an air-core single-mode hollow waveguide that uses 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 novel hybrid transmission-line medium that can be used in a variety of functional components for broadband millimeter-wave and terahertz applications.