Numerous papers experimentally verify the resonant characteristics and explain the resonant phenomena, such as the exploration of six different complementary structures with one resonant frequency  and the analysis of resonances in SRR with one or two resonant peak .
In the complementary structure, according to Babinet's principle , if we rotate the polarization of electric field and magnetic field by 90 degree, the structure can realize the pass-resonances [34-36].
Correspondingly, the Aluminum patterns in the STRR will be hollowed out in the complementary structure as shown in Figure 5(a).
Their work is about developing complementary structures
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