Simulation of two compact antipodal Vivaldi antennas with Radiation Characteristics enhancement

In this paper, two compact antipodal Vivaldi antennas (AVA) with improved Radiation Characteristics are presented. U-typed tapered slot edge (U-TSE) AVA and comb-shaped AVA with U-TSE are simulated and optimized. The -10-dB reflection coefficient bandwidth of comb-shaped AVA spans from 2.3 GHz to 18 GHz (7.83~1) and covers 15.7 GHz, while the bandwidth of conventional AVA which has the same dimensions spans from 3.3 GHz to 18 GHz (5.45~1) and covers 14.7 GHz. The U-TSE structure has the capacity to extend the low-end bandwidth limitation and improve the radiation characteristics in the lower frequencies. Compared with the conventional AVA, this modification can miniaturize the electrical size of the AVA antenna about 30%. The results regarding return loss, far field pattern, antenna gain and axial ratio are illustrated.