Broadband planar printed quasi-Yagi based on Vivaldi structure

This paper presents a planar printed quasi-Yagi antenna. The proposed antenna consists of a microstrip line slotline transition structure, a driver dipole and two parasitic stripes. The driver dipole is connected to the slotline through coplanar stripline (CPS) which is designed by using a pair of exponential curves and a circular groove end, just the Vivaldi antenna structure, so as to achieve a wide bandwidth. The ground plane is modified by symmetrically adding two extended stubs and cutting two blocks to adjust the matching with the dipoles. Experimental and simulated results show that the proposed quasi-Yagi antenna has a wide bandwidth and good unidirectional radiation characteristics. Compared with conventional printed quasi-Yagi antennas, the bandwidth is wider, from 2.9GHz to 10.1 GHz with a ratio of about 3.48? 1, and it´s front-to-back ratio greater than 10 dB. The antenna achieved a moderate gain, which is maintained from 4 dBi to 6.2dBi, and efficiency is mainly located at 90%, the minimum is more than 71%.