Design of miniaturized 2.5D frequency selective surface for X- and Ku-band applications

This paper presents the design of 2.5D frequency selective surface (FSS) for X and Ku band applications. Proposed FSS's unit cell is constructed with two independent slitted rings on both side of the FR4 substrate and is connected with metallic vias. The FSS offers a wide stop band performance from 6.26 to 18 GHz, with a fractional bandwidth of 96.7% measured at S-21 < -10 dB and has a low insertion loss (IL) of 0.018 dB. The footprint of the FSS is only about 0.11 lambda(L) with the shielding effectiveness of 83.365 dB, and the transverse electric and transverse magnetic mode performances are stable up to 70 degrees. Prototype FSS is fabricated and measured for its performance validation. The performance validation is carried out using applied wave research and the equivalent circuit model tools.