Beam-Forming Antenna Based on Electrically Reconfigurable Frequency Selective Surface

A linearly polarized two-dimensional beam-forming antenna using electrically reconfigurable frequency selective surface (FSS) has been proposed in this manuscript. The antenna structure incorporates a coaxial fed patch antenna and a reconfigurable FSS layer, kept above the patch radiator at a height of 0.41 lambda(0) (lambda(0) represents the free space wavelength at the resonant frequency). The reconfigurable superstrate FSS layer consists of 6x6 unit cells. The dimension of each unit cell is 0.24 lambda(0)x0.24 lambda(0). To make the FSS layer electrically reconfigurable, each unit cell consists of two PIN diodes. The FSS superstate is further divided in four sections and each section contains 3x3 unit cells. Each sections are connected to the individual biasing pads for the purpose of biasing. The overall dimension of the proposed structure is 1.6 lambda(0) x 1.6 lambda(0) x 0.44 lambda(0). When the reconfigurable FSS is illuminated by the coaxial fed patch, the composite system can generate thirteen individual radiating modes, which interms radiating in thirteen individual direction in 3D space. The antenna operates at a resonant frequency of 4 GHz and a maximum gain of 8.06 dBi is achieved with a maximum of 34 degrees tilting of the beam.