Design of miniaturised‐element FSS based on 2.5‐dimensional closed‐loop Hilbert fractal

A novel miniaturised frequency selective surface (FSS) unit cell is proposed based on the Hilbert fractal and 2.5‐dimensional (2.5‐D) metallic loop. For the increase of current path, both sides of substrate are used which are connected together by four vias. The dimension of FSS unit cell is obtained as 0.041 λ 0 × 0.041 λ 0 at the frequency of 2.47 GHz. The transmission coefficient is insensitive and independent of angle and polarisation of incident wave. A prototype model of the proposed FSS is fabricated and measured for the proof of concept. It is shown that it achieves better miniaturisation relative to the FSS reported in the literature.