Study On Electromagnetic Metamaterials Absorber And Polarization Transformer

Electromagnetic metamaterials(EMM) open up new realms and have become a hotspot in 21 century, which have been studied by general scholars. EMM are a kind of artificial composite structures with amazing electromagnetic properties. Through effective and appropriate design, some bizarre properties can be achieved by EMM in contrast to natural materials.Based on the theory about EMM, a number of electromagnetic metamaterial absorbers(MMA) are proposed in this paper, whose absorption property and physical mechanism are discussed. Meanwhile, we study the electromagnetic metamaterial polarization transformer structures and two models have been designed. The experimental results are in basic agreement with simulations. The main researches are as follows:By using metallic cross structure, two kinds of electromagnetic metamaterial absorbers have been presented. First of all, a triple-band electromagnetic metamaterial absorber is designed by the metallic cross structure and split square ring. There are three nearly unity absorption peaks at 8.90 GHz, 15.45 GHz and 16.55 GHz, with absorption rates of 99.89%, 99.86% and 99.99%, respectively.Apart from this, a wide-band electromagnetic metamaterial absorber is designed on basis of the fractal theory. The wide-band MMA presents good absorption above 90% between 21.12 GHz and 23.64 GHz.A well-shaped wide-band electromagnetic metamaterial absorber is designed by loading chip resistors. The MMA can present good absorption above 90% between 2.4GHz and 8.0GHz with a relative absorption bandwidth of 108%. The absorption property and the physical mechanism are studied by discusssing the four different imposed conditions.It can be determined that the absorption mechanism stemmed from the chip resistors.At last, two electromagnetic metamaterial polarization transformer structures are put forward.The surface resonance structures of two models are composed of cut-angle metallic square patches.The linear polarization conversion phenomenon is achieved,whose bandwith is from 8.85 GHz to 14.17 GHz by the first model and from 7.49 GHz to 16.03 GHz by the second model.The experiments of the two models show good agreement with simulations.