Strong absorption and high transmission Rasorber with wide-angle enabled by 3D-printing metastructure and three metasurfaces
摘要
The present investigation introduces a composite frequency selective Rasorber (CFSR) that demonstrates a wide −1 dB transmission band, two high absorption bands with absorptivity higher than 90%, and large oblique incidence angles up to 60°. The CFSR consists of four functional layers separated by three dielectric slabs, which includes lossless metasurface-I (MS-I), loss metasurface-II (MS-II), loss metasurface-III (MS-III), and a three-dimensional metastructure (3D-MS). MS-I functions as a reflector for two absorption bands with a minimal insertion loss transmission window. MS-II is designed for high-frequency absorption. MS-III serves as a low-frequency absorption layer for CFSR and an impedance matching layer for MS- II. The design methodologies for the transmission window in MS-III and the introduction of 3D-MS are key to achieving high-performance CFSR. The physical mechanisms of CFSR are explained through equivalent circuit model (ECM) analysis and impedance characterization. Finally, measurement results confirm that the proposed CFSR exhibits a −1 dB transmission band ranging from 8.79 to 10.41 GHz with a minimum insertion loss of 0.44 dB at 9.59 GHz; furthermore, the frequency range where reflection coefficient remains below −10 dB is measured to be between 3.33 and 18.00 GHz, aligning well with simulation outcomes.