Design of Miniaturized High Gain Bow-Tie Antenna

A high gain low-frequency bow-tie antenna with artificial magnetic conductor (AMC) and metamaterial lens for ground penetrating radar (GPR) is proposed. First, a bow-tie antenna working in 348-772 MHz frequency band is designed. The substrate is a square with side length of 420 mm. A periodic AMC reflector is designed. The in-phase reflection region of the unit is 481 MHz-1.44 GHz. The results show that the gain of antenna loaded with reflector is increased by 5 dB. A metamaterial lens based on the zero-index metamaterial element is also proposed to improve the gain. The zero refractive index frequency point is 810 MHz, the unit size of the metamaterial is 60 mm, and the lens size is consistent with the antenna substrate size. The gain of the antenna loaded with AMC reflector and the metamaterial lens is increased by 6.5 dB and the front-to-back ratio is 23 dB. The directivity of the antenna is further optimized. The measured results are in good agreement with the simulations.