Gain and SAR improvement of a conventional patch antenna using a novel Pi-shaped DNG metamaterial

Conventional microstrip patch antennas have several advantages such as low profile, light weight and low cost over the others, but lag behind in some criterion such as low gain and high SAR, where using metamaterials can be a possible solution. In this paper, a, antenna system is proposed where an S-shaped planar antenna, operating at frequencies of 11 GHz and 13 GHz, uses a Pi-shaped double negative metamaterial array, designed in CST, to improve its gain and SAR. In this system, metamaterial array is applied not as an antenna, but as an associating device for the planar antenna. This array can be implemented on a printed circuit board while maintaining a specific distance from the patch antenna. The gain of the antenna system is enhanced by 6.063 dB at 11 GHz (Increase of 1088.5%) and 3.77 dB at 13 GHz (Increase of 83.4%). The metamaterial array is placed between the antenna and a human-head model which clearly reduces the SAR by 1.379 W/kg at 11 GHz (Decrease of 99.99%) and 1.774 W/kg at 13 GHz (Decrease of 99.66%). This system is applicable for any X and K_u band applications such as satellite and Radar communications, where high gain and directivity is required. The negligible SAR value announces its capability of being used in any portable communication device where human-safety is a major concern.