PTD-Symmetric Double Edge Line Enabling Simplified Feeding and Integration With Gap Waveguides

Abstract

In this article, we propose a novel backscattering-protected PTD-symmetric waveguide in gap waveguide technology that addresses several challenges encountered in existing designs. The proposed configuration consists of two edge lines excited by a single mode—either even or odd—ensuring robust wave propagation while significantly simplifying the excitation mechanism. The waveguide leverages established PTD-symmetry principles while introducing a practical dual-edge realization that enables simplified excitation using standard waveguide feeders and is fully compatible with gap waveguide platforms. We provide a detailed discussion of the design, including the implementation of the required metasurfaces and the transitions necessary for efficient excitation. To validate the backscattering immunity, a bent waveguide prototype is developed, demonstrating low reflection over a relative bandwidth of 27.5%. A prototype is manufactured to experimentally confirm the robust propagation achieved in the waveguide. These results highlight the potential of the proposed approach to allow integration of PTD-symmetric waveguides with standard waveguide technologies, enabling new design possibilities.