Asymmetric Electromagnetic Absorption and Reflection Based on Transmissive Metagratings

We propose an asymmetric electromagnetic absorber and reflector design based on a transmissive printed circuit board (PCB) metagrating. By selecting the length of the supercell, the metagrating presents only the 0
^th
reflection diffraction mode and 0
^th
transmission diffraction mode. Then, by designing the meta-atoms composed of a microstrip capacitor and a lumped resistor on both sides of the dielectric substrate, the destructive interference between the 0
^th
reflection diffraction and specular reflection and between the 0
^th
transmission diffraction and direct ray transmission are achieved to realize the wave absorption effect under forward illumination. In addition, when the incident wave is incident from backward, a phenomenon of reflection is presented. The proposed structure does not contain any ground plane, which makes the design suitable for applications where the absorber should not block transmission outside the absorption band.