Ultra-Small Bent Meta-Waveguide Filters

This paper demonstrates the capability of locally resonant metamaterials (LRMs) for creating compact metallic waveguide E- and H-bends, which are simultaneously working as bandpass filters. For creating these bent meta-filters, we use composite pin-pipe waveguides (CPPWs), which are a type of LRMs made from resonant pins inserted in a rectangular waveguide. Like linear-shaped CPPWs, the subwavelength spatial dispersion in E- and H-bent CPPWs can nucleate a hybridization bandgap and subwavelength modes with custom frequency and bandwidth. To guarantee compatibility with standard waveguides and to improve the matching, we design subwavelength metamaterial ports. Finally, we build and test narrow and wideband H-bent CPPW filters, compatible with WR75 (10-15GHz) interfaces. Our measurements demonstrate the excellent performance of the small bent meta-filters and the customizability of the bandwidth. Our findings enable us to merge assembly components, such as bends and filters, in an ultra-small volume. It may find applications for reducing the size of waveguide networks with complex geometries in telecommunication and radar applications.