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Front-to-Back Ratio Enhancement of Planar Printed Antennas by Means of Artificial Dielectric Layers

In this paper, we investigate the use of artificial dielectric layers (ADLs) as a mean to enhance front-to-back radiation ratio in printed, planar antennas. These artificially engineered substrates can be designed to be anisotropic and present high dielectric constants for the waves propagating orthogonal to metallic layers. However, the dielectric constants is as low as that of the host material for the waves that propagates towards grazing direction, and thus surface waves due to multiple reflections at the dielectric air interface are not enhanced. A simple qualitative description of this concept is followed by the presentation of a experimentally verified prototype which clearly highlights the potential advantages of the proposed ADL for antenna applications.