Key Technology Of Electromagnetic Manipulation By Metasurface

Metasurface is such a kind of planar array that composed of subwavelength unit cells arranged periodically or non-periodically,which has strong ability to control electromagnetic waves,attracting more and more attention.In this dissertation,two kinds of metasurface that manipulate spoof surface plasmon polaritons(SSPPs)and spatial waves are investigated deeply,respectively.The main researches and contributions of this dissertation are as follows:1)According to the relationship between the dimension of the unit cell of SSPPs and its dispersion characteristic,a SSPPs-based conversion between surface wave and space wave is designed and experimentally verified.After the expansion of the unit cell,the omnidirectional leaky wave antenna is realized through the combination of the sinusoidal modulation surface impedance theory.2)The coupling mode in SSPPs is analyzed from the speculative knowledge,as well as its impact on the transmission characteristic of surface waves.It is put forward that the parallel coupling mode and series coupling mode can be used to realize band-pass transmission line and band-stop transmission line,respectively.The feasibility of the proposed method is verified through experiment.3)SSPPs transmission line is regarded as feed network of the antenna for the first time.Take advantage of the relationship between its dispersion characteristic and frequency,as well as the radiation feature of circular metal patch,a frequency scanning antenna based on SSPPs is designed and verified experimentally.The proposed frequency scanning antenna overcomes the shortcomings of traditional scanning antenna.The scope of application of SSPPs is expanded through this design.4)On account of the advantages of SSPPs as feeding system,the influence to electromagnetic waves from the radiation patch unit during the energy coupling process is also introduced to design vortex beam emitter.Compared with the common method to produce vortex beam,the proposed vortex beam emitter can produce different orbital angular momentum(OAM)modes at different frequencies,providing higher flexibility in OAM mode generation.Both the simulation and experimental results prove the accuracy of the proposed theoretical analysis.5)The automation of the co-simulation is accomplished through programming,providing great convenience to the design of unit cell of metasurface and the improvement of its performance.By using co-simulation,a reflection type polarization converter with ultra-wide bandwidth is designed and proved through experiment.6)The response to the electromagnetic waves of a new transmission metasurface is studied.A kind of circular polarizer unit cell is designed according to the different response to two orthogonal polarizations.Combined with the use of scale of the unit cells to control radiation patterns,a circular polarizer with beamforming feature is realized finally and also verified through measurement.7)The concept of shared-aperture and coding are introduced to the design of metasurface,offering a new idea to electromagnetic waves controlling.Several multi-functional coding metasurface is put forward based on these concepts.Transmission of multi-beam,independent transmission of vortex beam and normal beam,independent transmission of two orthogonal polarizations are achieved through this new design idea.