Improvement of Vivaldi Antenna in Microwave Imaging System

Vivaldi antenna has been widely used in the microwave imaging system due to its wide frequency range and low cross-polarization character. The directivity and transfer efficiency of the antenna in the system is of great importance to the imaging quality. The Vivaldi antenna is commonly connected to the coaxial line with an SMA connector. However, the SMA connector forms a coplanar waveguide structure on the substrate, which makes the center frequency shift and the return loss increase. Through simulation, it is found that removing the SMA connector pins can improve the efficiency of the system antenna at the working frequency. The simulation results are verified by actual measurements in the imaging system.