Low side lobe tapered slot antenna with high gain using gradient refractive index metamaterial for ultra wideband application

A novel broadband gradient refractive index (GRIN) metamaterial is used to improve the gain of the tapered slot antenna. The proposed metamaterial is capable of reducing the side lobe level of the antenna. The gradient refractive index (GRIN) metamaterial is constructed by using nonresonant parallel-line unit cells with different refractive index. Due to the non-resonant structure, the proposed unit cell exhibits low loss and large frequency bandwidth. The metamaterial, effective refractive index is lower than that of the substrate on which the antenna is printed. The GRIN metamaterial is integrated in front of the antenna which has the capability to manipulate electromagnetic wave accurately. The measurement results indicate that the reflection coefficient of the antenna is below -10 dB over the frequency band from 3 to 11 GHz. The radiation pattern of the antenna shows the beam width becomes narrow and directive with low side lobe level. The peak gain is increased by 2.1 dB at 9.5 GHz. The antenna has shown significant improvement on gain at low frequency. © 2017, Advanced Electromagnetics. All rights reserved.