Enhanced Bow‐Tie Antenna Array With Composite Reflector and Metamaterial Lens for GPR

ABSTRACT This letter proposed a high‐gain and high‐directivity bow‐tie antenna array (BTAA) with a composite reflector (CR) and a gradient refractive index (GRIN) lens. The CR is composed of two types of units with different mechanisms while the GRIN lens consists of eight metamaterial units with different refractive index. The measured results show that the maximum gain of the target antenna is 13.22 dBi, antenna gain is improved about 4.75 and 1.15 dB based on these structures, respectively. In addition, the minimum value of half‐power beamwidth (HPBW) in x O z plane is 37.1 degrees, the maximum value of the sidelobe level is ‐10.19 dB, the proposed antenna has a good directivity in operation band. The simulation and measurement results demonstrate that proposed antenna has a good application potential in shallow GPR systems.