Power transmission enhancement by means of planar meta-surfaces

Abstract

In this paper, the analysis and design of a planar meta-surface based on dipoles and wires is presented. The unit cell is formed by three layers, two parallel dipoles and one continuous wire. The transmission response and dispersion diagram of the unit cell are analysed step by step in order to determine the effect of each element; one dipole, two parallel dipoles and finally the two dipoles and wire unit cell. For a normally incident plane wave excitation with the E field parallel to the wires and the H field axial to the dipoles, a strong magnetic dipole moment is induced which produces a pass band around the resonant frequency and a stop band at higher frequencies. This cell is used to create meta-surfaces for antenna gain enhancement. Two configurations are analysed; the first one is a superstrate of a dipole antenna with the pass band tuned to the resonant frequency of the dipole. Due to the resonance of the superstrate inclusions, a uniform illumination is achieved, which produces high aperture efficiency and an increase of the directivity up to 6.31. By adding a meta-substrate with the stop band tuned to the resonant frequency of the dipole, an enhancement versus the conventional dipole of five times in the boresight radiation and 795 times in the front–back ratio is obtained.