Investigations On Graphene Based Frequency Selective Surfaces

Graphene is a new carbon nanomaterial with excellent properties in electromagnetics, optics, chemistry and mechanics, etc., which has attracted great attention. Theoretical researches on graphene have caused an upsurge in the scientific community, and the investigations of graphene devices are also gradually increasing, including graphene absorbers, graphene antennas and graphene frequency selective surfaces(FSSs), etc. The graphene devices operating within THz frequency range have small sizes, good performances and easy integrations. Further, since the surface conductivity of graphene can be adjusted by electrically and magnetically biasing, graphene devices can also be designed with tunability and giant gyrotropy. Therefore, this work is focused on tunable graphene FSSs for THz applications. The main contribution and novelty are summarized below:1. Researches on the electrically biased graphene FSSs. At first, the impedance and transmission characteristics of graphene patch and grid FSSs are investigated analytically with their circuit models. Then, a self-complementary FSS is constructed with graphene patch and grid structures. The transmission and tenability performances are explored. Further, a graphene grid-patch-grid sandwiched structure is designed. By adjusting the surface conductivity of the upper and lower graphene grid layers, the transmission characteristic of the whole FSS can be controlled effectively.2. Researches on the magnetically biased graphene FSSs. Firstly, the transmission of graphene patch and grid FSSs under magnetically biasing are studied. The circuit model is established for the magnetically biased graphene patch FSS. Its gyrotropy is analyzed and the model is validated by full-wave simulations. Then, a bilayer graphene patch-sheet FSS is proposed. The transmission characteristics is analyzed with those critical factors. The information of rotation angle is provided. The tunability with both electrically and magnetically biasing is investigated, and the tunable graphene FSS is designed with gyrotropy. By modifying the structure, the tuning ranges of central frequency and bandwidth are enlarged. The intensity of cross polarization is also guaranteed.The graphene FSSs biased with electric and magnetic fields are analyzed in this dissertation. The design principles and the tuning laws are presented. Accordingly, the tunable self-complementary and gyrotropic graphene FSSs are proposed using electrically and magnetically biasing, respectively. Both the design method and the prototypes of graphene FSS are provided for THz applications in this dissertation. This is an exploratory research, which is promising for related engineering scopes.