Compact Ultra-Wide Band Frequency Selective Surface With High Selectivity

In this communication, an ultra-wide band frequency selective surface (FSS) with excellent transmission performance in the desired passband and reflection performance in the out-of-band is proposed. In order to simultaneously achieve a wide bandwidth, as well as the better band-stop characteristic, a cascaded hybrid resonant element is employed to construct the FSS, which is composed of resonant circular rings and inductive meandering grid arranged on different layers. In addition, a fifth-order equivalent circuit model (ECM) is established over the entire band from 0.1 to 8 GHz, which can accurately describe the frequency responses. Finally, a prototype of the proposed design is fabricated and measured. The results show that a wide -3 dB bandwidth of 154.4% from 0.5 to 3.88 GHz is achieved. The -10 dB stopband is from 4.04 to 7.68 GHz and a sharp transition within 160 MHz from passband to stopband is obtained. The dimensions of the element are as compact as 0.0263λ× 0.0263λ at the starting frequency of the passband. All the results demonstrate the ultra-wide bandwidth advantage and excellent out-of-band reflection, steep roll-off, and miniaturization performances.