A novel compact multi-band frequency selective surface (FSS) with dual passbands and wide upper stopband is presented. The proposed FSS was originally a double-layer structure. The grid-double square loops (G-DSLs) are located at the bottom to achieve the dual passband characteristics. In order to realize wide upper stopband, a modified square ring and a Jerusalem cross (M-SR-JC) element structure at top and bottom are used. Considering the higher power engineering applications, the final FSS uses a multi-layer structure. The FSS provides two pass-bands centered at 3.8 and 5.8 GHz with relative bandwidths of 18.4% and 13.5%, respectively. It also provides wide stopband characteristics from 10.8 GHz to 14.5 GHz. The simulation and measurement are in good agreement. The novel FSS with dual passbands and wide upper stopband is compact; easy to design and fabricate, and achieves relatively stable multi-band response under different polarization states and different incident angles. The proposed FSS can better meet the engineering requirements.

A novel compact dual-band bandpass filter (DBPF) using SIRs with open-stub line and 0-degree feed structure is presented in this paper. The low-band is obtained by using hairpin type Stepped Impedance Resonators (SIR) split ring through electrical coupling ， And by tuning a pair of open-stub lines the high-band is realized too. In order to improve the stop band attenuation, zero-degree feed structure is implemented to introduce three transmission zeros. So the proposed DBPF has high selectivity, and is also simple in design and compact in structure. Finally the proposed filter is designed and fabricated, and the simulation and test results are in good agreement. Index Terms-dual-band filter, SIR, open-stub line, zerodegree feed structure.