Ultra-broadband Multilayer Microwave Absorber by Multimaterial 3D Printing

In this paper, an ultra-broadband microwave absorber, covering the C-band, X-band and Ku-band, has been proposed and investigated. The innovative nature of this absorber is based on the combined use of multilayer structure and multimaterial 3D printing technology. The designed unit cell is a stack of 22 pairs of layers made of metal and dielectric square patches with a total thickness of 13. 5mm (half of centre wavelength). Two dielectric materials with different relative permittivities (2.6 and 8.0) are used to obtain ultra-wideband behaviour. The simulation results show more than 93% absorptivity over an ultra-wideband from 3.5 to 18.5 GHz (corresponding to a fractional bandwidth of 1.36). The structure offers a good robustness under oblique incidence with more than 80% absorptivity from 4.0 to 18.5 GHz up to $45^{\mathrm {o}}$ in both TE and TM polarisations. The paper demonstrates a new way to design and manufacture promising low profile and ultra-wideband absorbers for microwave applications.