Ultra-broadband and wide-angle ink-coated truncated cone metamaterial microwave absorber

Expanding the bandwidth for microwave absorption at wide incident angles across the S to V bands presents a significant challenge. In this paper, an ultra-broadband and wide-angle ink-coated truncated cone metamaterial microwave absorber was proposed. The unit cell of the proposed absorber consisted of a polylactic acid (PLA) truncated cone coated with resistive ink, a PLA substrate, and a copper plate. The numerical simulation results showed that more than 90% absorptivity can be achieved in the frequency range of 1.4–70 GHz under normal incidence, with a relative absorption bandwidth of 192%. Furthermore, the absorption performance was insensitive to the incident angle. When the incidence angle increased from 0° to 60° for TE and TM waves, over 90% absorptivity was achieved in the frequency range of 2.2–67.2 GHz. Absorption bandwidth ranges from the S to V bands. The resistive ink coating on the truncated cone plays a crucial role in enhancing absorption and broadening the absorption bandwidth across the entire spectrum. The absorption mechanism of the absorber was analysed through the graded impedance matching theory. Additionally, the ink-coated truncated cone metamaterial absorber sample was fabricated, and the proposed design was validated through experimental testing. The proposed ultra-broadband and wide-angle metamaterial absorber offered potential applications in the field of radar and flight vehicle stealth.