Multi-Layer Filter Arrangement

An electromagnetic filter arrangement comprising a plurality of stacked layers, the stacked layers comprising:

• a top layer,
• a bottom layer,
• a filter layer arranged between the top layer and bottom layer,
• at least one upper layer arranged between the top layer and the filter layer,
• at least one lower layer arranged between the bottom layer and the filter layer,
• wherein the top layer comprises a first opening and the bottom layer comprises a second opening, the second opening being displaced from the first opening, when seen in a direction normal to a longitudinal plane, the longitudinal plane being parallel to the stacked layers,
• wherein at least one of said at least one upper layer and at least one of said at least one lower layer comprises an elongated aperture forming a waveguide channel, each waveguide channel extending so as to overlap, when seen in a direction normal the longitudinal plane, with the first and second opening, respectively,
• wherein the filter layer comprises a first set of filter apertures, the filter apertures of the first set being arranged along the waveguide channels of the at least one upper layer and the at least one lower layer, and
• wherein a metasurface is arranged between the at least one upper layer and the filter layer and between the at least one lower layer and the filter layer, respectively, wherein the metasurfaces surrounds the waveguide channels and wherein the metasurfaces comprise a plurality of thick and thin sections.