A miniaturized Vivaldi antenna by loading with parasitic patch and lumped resistor

A miniaturized Vivaldi antenna is presented in the paper. On the basis of original antenna, the miniaturized Vivaldi antenna applies parasitic patch and lumped resistor to improve impedance characteristics. The proposed load can expand the lower operating frequency to 1.96 GHz without changing antenna dimensions. The size of antenna is set as 43 × 40 mm2. This size is about 0.28λL × 0.26λL, where λL is the free space wavelength at 1.96 GHz. The loaded Vivaldi antenna is fabricated and measured. The simulated and measured results clarify the viability and effectiveness of the proposed design. The measured impedance bandwidth (VSWR ≤ 2) is from 2 GHz to more than 18 GHz. In addition, the measured radiation patterns and a peak gain between −1 and 9 dB can be obtained in the band of 2-18 GHz.