Broken Glide-Symmetric Holey Structures for Bandgap Selection in Gap-Waveguide Technology

In this letter, we propose a new technique to tune the bandgap in gap-waveguide technology based on broken glide-symmetric holey structures. We demonstrate that breaking the glide symmetry in a proper manner provokes the presence of a passband within the bandgap due to the frequency sweep of the second propagating mode. This passband generates field leakage in the gap that is translated into a filtering property. This filtering effect may be used to reduce or eliminate filters in large complex devices. In order to avoid undesired coupling due to the leakage from the air gap between the plates, an absorbing sheet is proposed to dissipate the undesired fields. This idea has been numerically studied and experimentally validated with a specific design, a WR15-size gap-waveguide prototype with glide-symmetric holes with filtering properties.