FREQUENCY SELECTIVE SURFACE DESIGNED USING ELECTRIC RESONANT STRUCTURES IN TERAHERTZ FREQUENCY BANDS

Electric resonant structures are primary unit cells to construct single negative permittivity metamaterials, which are also widely used in the design of novel microwave components. In this paper, the relative equivalent circuit model is first studied, the resonant characteristics of such structure is analyzed, the factors effected on the distribution of zero and pole transmission points are presented, based on which a realizable way to design filters with narrow transition-band from stop-band to pass-band is elicited. Then, a frequency selective surface (FSS) is designed with -36.9 dB attenuation in 40 GHz near the working frequency of 0.7 THz. The S parameters are also compared with those of a conventional electric resonant structure, from which we observe that the later has larger size besides wider transition bandwidth. On the other hand, the novel FSS can increase the utilization factor of frequency spectrum. In order to further decrease the transition bandwidth, three layers of the FSS structures are arrayed. By tuning the distance between each two layers, much narrower bandwidth is easily achieved which can be reached to 10 GHz.