Ultra-wideband Antipodal Tapered Slot Antenna with Gradient Refractive Index Metamaterial Lens

This letter proposes an ultrawideband and high-gain antipodal tapered slot antenna (ATSA) with a gradient refractive index (GRIN) lens. The GRIN lens consisting six metamaterial lenses is placed in the maximum radiation direction of the ATSA to greatly enhance its radiation capability. We found that the proposed GRIN lens antenna has a wide impedance bandwidth of 175.7% (0.84–13 GHz) and −3 dB gain bandwidth of 65.8% (5.86–11.6 GHz). Its gain is averagely increased by 4.81 dB in the whole operating band, and the maximum gain reaches 20.55 dBi at 9.5 GHz. The simulation and measured results demonstrate that the designed GRIN lens antenna has an excellent performance and is suitable for short-pulse ground penetrating radar systems.