Research on broadband absorbers based on 3D printing and conductive thin films

A broadband absorber based on 3D printing is proposed. Polylactic acid (PLA) and conductive PLA are employed to construct a hollow square pyramid nested inside a hollow cube. The absorber achieves average absorptivities exceeding 90% and 99.3% over 8.1–18 GHz and 11.66–18 GHz, respectively. Analysis of the electric-field distributions inside the structure shows that reflections and resonances formed at different locations by electromagnetic waves of different wavelengths are responsible for the broadband absorption. The absorber is polarization-insensitive and exhibits a certain degree of wide-angle incidence stability. After analyzing selected structural parameters, the fabricated sample is characterized using the free-space method. Subsequently, a broadband absorber based on an indium tin oxide transparent conductive film is proposed. The absorber consists of ITO, PET, and PDMS, all of which possess a certain degree of flexibility and visible-light transmittance. This absorber also exhibits polarization-insensitive and wide-angle-incidence characteristics. The sheet resistance of the conductive film and selected structural parameters are further investigated.