A Flexible Ultra-Bandwidth Non-Uniform Periodic Absorbing Structure

Narrow bandwidth is a fundamental issue plaguing practical applications of metamaterial absorbers. In this paper, We propose a non-uniform periodic absorbing structure that can greatly expand the bandwidth. Based on the consistency of Equivalent Circuit (EC) model simulates traditional single-layer metamaterial absorber, we designed a double-lobe non-uniform periodic flexible absorber structure, and first proposed and verified its EC model and explained the mechanism of three absorption combinations in the working frequency band to extend the absorption bandwidth. To expand the bandwidth, we also designed a single-lobe model, the simulation results show that single-lobe non-uniform periodic absorbing structure achieves a reflectivity of less than -10 dB (that is, the absorptivity reaches 90%)in the range of 4.1-19.3 GHz. Its fractional absorption bandwidth is 129.9% and the total thickness is 0.0845λ
L
(where λ
L
is the wavelength at the lowest frequency.). It is also demonstrated that the EC model is also suitable for guiding the design of such non-uniform structures. We expected that the design method proposed can be universally used in the design of metamaterial absorbers.