In this study,a design method of multilayer structure composite absorber based on double layers of meta-surface is proposed.The designed composite absorber consists of two layers of metasurface,top absorption enhanced skin and several support dielectric slabs.The unit cells of metasurface Ⅰ and Ⅱ are separately irregular-shaped metal patches connected by chip resistors and hexagonal metal rings loaded with chip resistors;the top absorption enhanced skin is a fiber-glass enforced epoxy laminate;support dielectric slabs adopt PMI foam.The simulation results indicate that the absorption frequency bands with reflection coefficients below-10 dB and-20 dB are 2.80～23.64 GHz and 3.56～22.56 GHz,respec-tively.The measurement results show that,the absorption frequency bands with reflection coefficients below-10 dB and-20 dB are 2.36～23.87 GHz and 3.17～23.16 GHz,respectively;the reflection coefficient curves obtained by simulation and test have good consistency,which verifies the effectiveness of the design method.The simulation and test results show that the frequency band of-10 dB reflection coefficient at 50° oblique incidence is basically consistent with that at normal inci-dence,while the offset of start and stop frequencies is less than 0.8 GHz;further,the simulation and test results show that when the oblique incidence angle is 60°,the fractional bandwidth of the reflection coefficient below-10 dB is up to 141.8％,which indicates that the composite absorber designed in this study has the incidence stability in a wide angle range.In addition,the mechanism of ultrawideband and high absorption of the structure and the influence of the main structure pa-rameters are analyzed;the results demonstrate that the top absorption enhanced skin can improve absorptivity of the whole structure by up to 0.2(1.0 represents 100％absorption),and the complementary enhancement design of the two layers of metasurface absorption frequency bands can improve oblique incidence stability obviously.
维普
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