A High-Selective Frequency Selective Surface With Hybrid Unit Cells

In this paper, a novel frequency selective surface (FSS) is proposed. It has two metal layers and the configurations of the unit cells of these two layers are different, so-called hybrid unit cells. The designed FSS has three transmission zeros and steep roll-offs at the edges of the passband. In our design process, the top layer is used to achieve two transmission zeros at the edges of passband and the bottom layer is used to achieve wideband performance and transmission zero at the right side of the passband. The effects of the geometrical parameters on the frequencies of transmission poles and zeros are analyzed. By establishing an equivalent circuit, the matching impedance network is obtained quickly by Microwave Office and the flatness and insertion loss of the passband are improved after introducing the matching impedance network. The prototype of the proposed FSS is manufactured and tested. The measured -1.5-dB passband is from 13.2 to 19 GHz, and its relative bandwidth can achieve 36%. The measured results verify the design. This FSS is a good candidate to strengthen the performances of Ku-band satellite and Ku-band active radar.