Reconfigurable frequency selective surface based absorber realized using interlocking blocks

A reconfigurable frequency selective surface (FSS) based absorber structure has been designed using a novel, cost-effective, simple to operate and easy to fabricate 3D printed interlocking blocks. Four different topologies have been investigated and validated through simulation and experimental studies. The basic geometry comprises a 3D printed mounting board, on which different blocks can be attached using interlocking studs. The frequency reconfigurability has been obtained by mechanically changing various resonating blocks on the board, which results in four distinct absorption frequencies at 4.89 GHz, 4.02 GHz, 2.92 GHz and 2.25 GHz achieving the absorptivities of 98.92 %, 96.52 %, 99.3 % and 99.5 % respectively in S and C bands. The absorption characteristics are further justified by evaluating the surface current distribution and impedance responses. The prototypes have been fabricated and tested, and they have attained a good agreement with the simulated responses. The absorption characteristics and operational frequencies remain the same, for all four cases during variations in the polarization angle for oblique incidence for both TE and TM polarizations up to 45 degrees, as studied in the simulation. These have been experimentally verified up to 30 degrees for TE polarization, thereby demonstrating the polarization-independent and angularly stable responses.