Employment of artificial magnetic metamaterials to effectively reduce the back-lobe of patch antennas

In this article, we present the employment of a proper set of artificial magnetic inclusions to dramatically reduce the back-lobe of patch antennas. The layout consists of a regular microstrip antenna surrounded by split-ring resonators (SRRs). These artificial magnetic inclusions are designed in order to resonate at the antenna operating frequency so that the surface waves are blocked and the front-to-back ratio of the antenna is increased. A numerical investigation of the near-zone magnetic field is conducted in order to propose a suitable arrangement of the SRRs around the antenna, aimed to obtain an effective 2D-isotropic suppression of the surface waves. Since inclusions located at the periphery of the structure resonate at a higher frequency, multiple split-ring resonators (MSRRs) are also used in order to reduce the resonant frequency of the peripheral inclusions. Finally, full-wave numerical simulations confirming the effectiveness of the proposed design and showing how the resonating artificial magnetic inclusions surrounding the antenna effectively suppress the back-lobe are presented.