A VHF Ultra-wideband Vivaldi Antenna with Loading Structure for EMC Test

In this paper, a VHF ultra-wideband Vivaldi antenna with loading structure for electromagnetic compatibility (EMC) test is proposed. The antenna is composed of a half traditional Vivaldi antenna loading corrugated edge and a metal ground. According to the principle of image, the size of the Vivaldi antenna can be reduced to half due to the application of a metal ground. In addition, the corrugated edge is introduced to reduce the lowest operating frequency. The electrical size of the proposed antenna is $0.68\lambda_{0}\times 0.21\lambda_{0} (\lambda_{0}$ is the wavelength of lowest working frequency in free space). The lowest operating frequency is reduced and radiation directivity is improved due to the corrugated edge. The performance comparison between the antenna with loading structure and the traditional one and the influence of loading corrugated edge are analyzed in the paper. The simulation results show that the cut-off frequency is reduced from 162.8 MHz to 127.4 MHz with 21.7% fractional bandwidth. In the VHF band, the maximum gain of the antenna can reach 9.67 dBi.