A high gain patch antenna using near zero-index metamaterial coating

In this paper, a high gain patch antenna using a near-zero-index metamaterial (NZIM) coating is presented for operating at 4.35 GHz. The proposed NZIM unit-cell is investigated and analyzed by both theoretical and numerical methods. It is shown that the designed NZIM unit-cell has a near refraction index characteristic at 4.25-4.45 GHz, which overlaps with the operating bands of the reference antenna. By covering a single layer NZIM coating with 4×4 cells over a conventional microstrip antenna, a gain enhancement of 2.8 dBi is achieved in comparison with the original antenna.