Defect induced co-polarization broadband metamaterial absorber

We propose a simple and new approach to design the broadband metamaterial absorber (MA) based on FR-4 substrate. The defected resonant patch of symmetry MA unit cell has been conceived to achieve the broadband absorbance. The simulated results demonstrate that the defected absorber structure exhibits the co-polarization broadband absorption response with absorptivity higher than 90% in the range of 4.0 - 6.0 GHz and the relative absorption bandwidth (RAB) of 40% for normal incidence. Furthermore, the defected structure can maintain the absorbance above 80% for oblique incidence up to 50° under both transverse electric (TE) and transverse magnetic (TM) polarizations. The compact structure (unit cell dimension of ∼λ/5.5 and thickness of ∼λ/20.8 with respect to the lower resonant frequency) and co-polarization broadband absorption with wide incident angle insensitivity of the absorber design based on defect make it suitable for defense system applications. Furthermore, this approach can be used to design co-polarization broadband absorbers in the terahertz, infrared and optical frequencies.