Investigation of metasurface using fishnet and closed ring structures on microstrip-fed slot antenna

Two types of resonator with fishnet and closed ring structures are combined in a square unit cell, resulting in ENG, MNG, and NZI properties on metasurface (MS). Moreover, Minkowski fractal pattern is applied on square fishnet (SF) surface for MS miniaturization. In term of MS investigation, it is placed on a microstrip-fed slot antenna (MFSA) as radiator. Obviously, the MFSA with metasurface can generate slot and cavity resonant modes, resulting in bandwidth enhancement of 1.11–1.44 GHz. Electromagnetic (EM) wave behaviors on MS are probed via results of antenna radiation patterns in operating frequency. Fortunately, the MS can induce MFSA to provide three different radiations including of unidirectional pattern peaked at 180 degree with ENG, bidirectional pattern with NZI, and unidirectional pattern peaked at 0 degree with MNG.