Compact miniaturised-element frequency selective surface

A compact miniaturised-element frequency selective surface (FSS) is proposed for size reduction. The proposed structure can be considered as a common square-loop slots FSS overlaid with a periodic array of metallic patches mounted on an ultra-thin dielectric layer. A larger coupling capacitance is brought in each overlap area between the two layers of parallel metallic films. The theoretical analysis and simulation results, together with measured results, demonstrate that a much better compactness characteristic can be realised in the proposed FSS.