Bandwidth-enhanced polarization-insensitive metamaterial absorber based on fractal structures

This paper presents a broadband polarization insensitive prefect metamaterial absorber based on fractal structures. Through the combination of fractal and circular structure, the bandwidth is extended without increasing the size of the unit cell. A simple equivalent circuit model has been proposed describing the absorption phenomenon to predict the frequency of absorption of the proposed absorber. The simulated result shows that the absorber's full width half maximum is 18.5%. With rotational symmetry structures, the absorber is insensitive to the polarization. The incident angles at which the metamaterial absorber can maintain 50% of the absorbance are up to 50°. With the geometrical scalability, the absorber can be extended to any frequencies. This absorber is fabricated and measured at X-band, and the experimental results coincide well with the simulation results.