Design and optimization of the antenna applied for detecting the voids in tunnel lining by GPR

In this paper, a new Antipodal Vivaldi antenna has been designed to be used for detection of the voids in tunnel lining by Ground penetrating radar (GPR). In order to obtain a desirable antenna performance, the wider impedance bandwidth, the higher radiation efficiency and gain, three parameters of the antenna structure, including a) length of microstrip line L, b) tapered slot opening rate R, c) elliptical axis radius R_e have been chosen to optimize the qualities of antenna based on FDID method. Moreover, the optimal Antipodal Vivaldi antenna has been used to detect the void in tunnel lining, and it´s proved that the new antenna has a good level of matching with the tunnel lining.