Gain enhancement of the ultra-wideband tapered slot antenna using broadband gradient refractive index metamaterial

In this article, a broadband gradient refractive index (GRIN) metamaterial is designed and used to enhance the gain of the tapered slot antenna (TSA). The proposed GRIN is implemented using nonresonant parallel-line unit cell with different refractive index values. GRIN lens are placed in front of the tapered slot direction in the direction of x-axis. The designed GRIN metamaterials have broad bandwidth (2-12 GHz) characteristics due to the nonresonant parallel-line elements which is suitable for the ultra-wideband frequency band. The measurement results indicates that the radiated beam becomes more directive with narrow beam width. The measured reflection coefficient is below -10 dB over the frequency bandwidth of 3-11 GHz. The peak gain of TSA is obtained up to 14 dB at 10 GHz using GRIN lens.