Low-frequency intertwined spiral-aperture absorbers for Shielded enclosures

A novel Frequency Selective Surface (FSS) is proposed for the design of polarization-insensitive metamaterial absorbers that operate below 1 GHz, where the first resonances of small commercial enclosures take place. The novel FSS shows a strong sub-wavelength response, enhanced by the dielectric substrate, which allows the design of compact planar absorbers with excellent angular and polarization stability.