| The manipulation of electromagnetic wave is the eternal demand of human beings.With the development of science and technology and the improvement of the demand for military and civilian use,the dynamic manipulation of electromagnetic wave has become increasingly important.In the microwave band,which is widely used in current equipment,the dynamic control of electromagnetic wave mostly depends on PIN tube,variator tube and other lumped devices,the necessary welding process restricts the development of electronic devices to the goal of light,thin and soft to a certain extent.Graphene,a new material developed in 2004,the thickness of which is only nanoscale.In addition,graphene is a semiconductor material with good tunable conductivity.Thus it can meet the requirement of light,thin and soft and it is expected to replace the existing lumps to achieve dynamic control of electromagnetic waves.Under this background,we have carried out research on two-dimensional materials,especially graphene,at the microwave band.The contributions and innovations of this paper can be summarized as follows.1.The tunable conductivity of graphene and its research value in the electromagnetic field are introduced,the synthesising,transfering,patterning,and testing methods are summarized and analyzed.Especially,the methods used by our lab are introduced in detail.These contents are the theoretical and experimental basis for the study of graphene in microwave band.2.The graphene-based microwave amplitude manipulation was studied.A method to prepare patterned graphene by pre-patterned metal foil is proposed.An absorber based on the graphene frequency selective surface and a wide-absorption-medium-transmission device based on the graphene/metal mixed surface are realized.In this research,we derive impedance matching conditions for absorbing applications,which play a role in theoretical support for the design and analysis of the two applications.3.The graphene-based microwave polarization manipulation was studied.The influence of graphene impedance on the polarization state of electromagnetic wave was studied systematically.The polarization state of reflected wave was transformed from linear to circular by changing the sheet resistance of graphene.It proves that the phase control can be carried out effectively by changing the resistance characteristics of the material,which lays a foundation for the application of graphene-based microwave phase control.4.The graphene-based microwave wavefront manipulation was studied.In this process,we derive the necessary and sufficient conditions for realizing the binary coding unit by using resistive materials,which has the same amplitude and oppisite phase.This result provides a fast design method for resistive materials based beam control.Based on which,a static verification of microwave beam redirection using graphene ribbon array is firstly conducted,which shows the feasibility of graphene in this field.Subsequently,the dynamic control of the microwave wavefront is realized by properly designing the graphene-metal hybrid metasurface.The related research results mentioned above were published on journals,IEEE Transactions on Antennas and Propagation?IEEE Transactions on Microwave Theory and Techniques?ACS Photonics.I'm the first author of six papers.Moreover,the related researches were published on the international conferences,i.e.International Conference on Microwave and Millimeter Wave Technology(ICMMT 2018)?Proceedings of the 2019 IEEE Asia-Pacific Microwave Conference(APMC 2019)?2019 International Symposium on Antennas and Propagation(ISAP 2019),and I'm the first author of three papers. |
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