Seamless Waveguide Bends with In-Line Metasurfaces

We present a synthesis scheme for metasurfaces (MS) for perfect transmission of waveguided modes through sharp bends in rectangular metallic waveguides (WG). Uncommonly, the MS is utilized as an in-line component, placed at the bend discontinuity. The inherent symmetry of the configuration allows retaining the modal integrity while locally conserving the power across the MS, facilitating passive lossless design via previously developed analytical methods. Verified using full-wave simulations, this approach is found to yield unitary transmission efficiency across the bend, laying the ground for future explorations of WG-integrated MSs for mode manipulation.