In this work, we propose to use a type of periodic structures, the soft surfaces in their planar version, to reduce the back radiation of patch antennas. A key aspect of these surfaces when compared to other periodic structures is their anisotropy which provides different behaviour for different field polarization (horizontal or vertical). This make them especially convenient for this application, as the soft surfaces force the field intensity for any polarization to be zero on the surface for waves propagating along the surface. In this paper, a design example is presented and the back radiation reduction by using planar soft surfaces is demonstrated.
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