Study on capacitor-based reconfigurable FSS and its characterization

The study on capacitor-based reconfigurable frequency selective surfaces (FSS) and its characterization is presented in this paper. The study is mainly focused to analyze behaviour of capacitor in controlling the characteristic response of FSS structure. As the basis construction of reconfigurable FSS structure, a rectangular patch with the width of 0.6mm and the length of 130mm is applied. Three frequency ranges frequently used in wireless communications, i.e. GPS (1.575GHz), GSM1800 (1.8GHz), and WLAN (2.4GHz), are used for investigating the characteristic of FSS structure. In the study, at first, the patch shape of FSS structure is numerically analyzed using an initial structure divided into 2 identical parts. Then, some capacitive grids are added into the FSS structure to decrease its resonant frequency. Lastly, a capacitor with varied value is put in the gap between 2 identical patches to obtain the characteristic response of capacitor-based reconfigurable FSS. The characterization result shows the frequency shift around 40MHz and 50MHz at the frequency of 1.575GHz and 1.8GHz, respectively, while the frequency of 2.4GHz is always passed. The result is very useful for some applications which require only a specific frequency band, for example 2.4GHz, while suppressing other unwanted frequency bands.