Experimental analysis and comparison between cross-shaped metamaterial absorber and its complementary structure

In this article, cross-shaped metamaterial absorber (CSMA) and its complementary structure (CCSMA) with uniform parameters are experimentally analyzed in details. Perfect absorptions with intensities over 99.5% have been achieved at 4.99 GHz for CSMA and 5.39 GHz for CCSMA, respectively, both of which are equipped with polarization insensitive performance. For transverse electric (TE) mode, the parameter FSOIAs (frequency sensitivity of oblique incident angles) of these 2 absorbers is nearly the same with little values. However, the absorption peaks of the complementary one shift obviously to lower frequencies with wider transverse magnetic (TM) incident angles, and the FSOIA reaches up to 0.98% in simulation (0.66% in experiments), which is nearly 5 times stronger than that for TE situation. Besides, detailed comparison about the effective material parameters including relative permittivity, permeability, and relative impedance have been conducted by S-parameter retrieval method. Microwave experiments are performed to successfully demonstrate the numerical results.