Design of 2.5D Miniaturized Broadband Absorber for Ultrahigh-Frequency Band

A broadband metamaterial absorber (MA) structure for Ultrahigh-Frequency (UHF) band was proposed, and the miniaturization of the unit was realized by combining the method of bending metal wires and loading metal vias. The size of the unit cell is 0.040 λ_L × 0.040 λ_L × 0.075 λ_L (λ_L is the wavelength corresponding to the lowest frequency of 0.5 GHz). The simulation results show that the bandwidth of the MA is from 0.50 GHz to 1.33 GHz, and the relative bandwidth is 90.7%. Polarization insensitivity of the MA was realized through assembling a 2 × 2 orthogonal array. TE and TM polarizations maintain more than 80% of the absorptance in the range of 40^◦ at oblique incidence. The consistency of full-wave simulation, circuit simulation and measured results is high, which verifies the broadband absorption characteristics of the proposed MA.