Research On The Applications Of Metasurfaces In Reverberation Chambers

Metasurfaces are the two-dimensional counterpart of metamaterials.They have been the research hotspot in the fields of electromagnetic,optics,acoustics in recent years.According to the generalized Snell's law,the anomalous refraction and reflection of waves can be realized by introducing phase discontinuities into the metasurface structures.And the propagation characteristics of electromagnetic waves can be controlled flexibly based on specified metasurfaces.This dissertation makes full use of the metasurface for flexible tuning electromagnetic wave in the design of reverberation chamber---a well known platform for electromagnetic compatibility testing.Specifically,through simulations and experimental verifications,we investigate the matasurface as stirrers in improving the field uniformity in reverberation chambers.In this scheme,we try to set up the theoretical basis of metasurfaced reverberation chamber and put it into real applications.The main contributions of this study are as follows:1.The metasurface with uniform unit cell is attached to the inner wall of the reverberation chamber to study its influence on the reverberation performance of the reverberation chamber in the low frequency band.Firstly,the spectrum of the field uniformity in the reverberation chamber with uniformly distributed unit cells is obtained through simulations.And we analyze the reasons for improving the field uniformity from the aspects of mode number,total scattering cross section and Q value.Finally,the field uniformity of reverberation is tested in a real reverberation chamber and compared with the simulation results.2.The 1-bit coding characteristics of phase gradient metasurface are studied and applied in improving the low-frequency field uniformity of the reverberation chamber.We also analyze the reasons for the improvement of field uniformity based on the total scattering cross section and Q value in the phase gradient metasurface reverberation chamber.3.The 1-bit encoded metasurface tuned by diodes is studied,which has different effects on the reflection characteristics of electromagnetic wave.By attaching electrically controllable and coded metasurfaces to the walls of the reverberation chamber and controlling the on/off state of diodes through FPGA,we can emulate the metallic stirrers to generate enough cavity modes,thus leading to a new type of reverberation chamber--Active Metasurface Reverberation Chamber.This reverberation chamber can effectively enlarge the testing space of the reverberation chamber with the same field uniformity.