Improvement of gain in compact antipodal Vivaldi antenna

In this paper, the reduction of the size of antipodal Vivaldi antenna and the improvement of the gain are discussed. First, the miniaturization of antipodal Vivaldi antenna is achieved by increasing the size of the ground plane and designing the two radiation elements asymmetrically. Next, in order to improve the gain, the small rectangular elements are installed in front of the antenna. Moreover, to achieve the uniform gain level, one rectangular element and one L-shaped element are installed at the area between the small rectangular elements. The impedance bandwidth of the antenna designed by simulation is 95.1%. The minimum and maximum absolute gains are 2.0dBi and 4.7dBi. The width of the antenna is 0.44 lambda(L )(lambda(L) is a wavelength at the lowest frequency). The proposed antenna is suitable to element of Array antenna.