A frequency selective surface with a very wide stop band

In this paper we investigate a very wideband, single-layer, low-profile frequency selective surface (FSS) reflector. The unit cell is simple and consists of a cross-dipole and a ring made on the opposite surfaces of a single substrate layer. The proposed design exhibits a broad stop-band of 7.5 GHz, from 6.5 GHz to 14 GHz. Its refection coefficient has a linearly decreasing phase over a large bandwidth. The compact configuration provides the flexibility for mounting the reflector close to a planar bidirectional UWB antenna such as a slot antenna, to make it unidirectional, by reflecting the waves radiated towards the FSS.