Fabrication and absorbing property of the tower-like absorber based on 3D printing process

The tower-like absorbing structures were designed and fabricated by the 3D printing process to achieve the good absorbing property and low density. The absorbing composite was composed of the carbonyl iron particles (CIPs) and the polylactic acid (PLA). The scanning electron microscopy was done to characterize the composite morphology, and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability of the printed wires were measured using a vector network analyzer, and the permittivity and permeability of the hollow composite were derived, the reflection loss (RL) of the composite could be simulated. The results showed that the tower-like absorbing structure had the good absorbing property, and based on the printing pathway the density of the composite could be decreased as the filling ratio was set. The frequency band (RL < −10 dB) was 12.9–18 GHz with filling ratio 70% and 9.5–18 GHz with filling ratio 100%. While as the microwave was oblique, the tower-like absorber had the better absorbing property as the incident angle was larger than 70°, the oblique RL was less than −20 dB in 12–18 GHz, which was about 11.2 dB lower than that of the simple pyramid.