A Printed UWB Vivaldi Antenna Using Stepped Connection Structure Between Slotline and Tapered Patches

In this letter, a new stepped connection structure between slotline and tapered patches is adopted in a planar printed Vivaldi antenna. By using the stepped connection structure, the impedance matching is significantly improved and a wide bandwidth is achieved. In order to illustrate the effectiveness of this design, a prototype of the modified Vivaldi antenna is fabricated and tested. Experimental results show that the impedance matching is significantly improved in the band from 3 to 15.1 GHz. In addition, a measured gain, which is better than 5 dBi, is obtained with a compact size. Compared to other techniques, the presented technique effectively improves the impedance matching and enlarges the bandwidth without changing the overall dimensions. Moreover, a relatively flat group time delay response is achieved within the band of 3-15.1 GHz.