Wideband and polarization-insensitive metamaterial absorber with loading lumped resistors

IWe have designed, simulated, and experimentally tested a broadband metamaterial absorber loaded with lumped resistors in the microwave range. Compared with an electric resonator structure absorber, the composite absorber loaded with lumped resistors has stronger absorptivity over an extremely extended bandwidth. The simulated results show that an effective absorption bandwidth covers from 7.12 to 8.61 GHz with the absorption rate more than 90% under normal incidence. For oblique incidence, the proposed absorber displays an absorption rate above 90% from 7.55 to 8.61 GHz when the incident angle is below 35° for the transverse electric polarization. About the transverse magnetic polarization, the absorber displays larger than 90% absorptance from 7.24 to 8.61 GHz when the incident angle is below 70°. During the entire design process, the absorber structure is fabricated and measured. The measured results show that the absorptivity is above 90% in the frequency range of 6.78–7.65 GHz and 8.20–9.31 GHz under normal incidence. Furthermore, the absorption mechanism and absorption properties are further researched.