A Modified UWB Antipodal Vivaldi Antenna with Improved Radiation Characteristics

In this paper, a modified antipodal Vivaldi antenna is presented for UWB applications. To extend the low-end bandwidth limitation and improve the radiation characteristics in the lower frequencies, a novel elliptical slot edge (ESE) structure is employed. The addition of ESE structure helps the antenna lower the low-end operating frequency by 570 MHz with the dimension unaltered. In addition, a pair of planar directors is used to improve the value of gains at high frequency bands. The proposed antenna achieves a-10 dB vertical bar S-11 vertical bar with bandwidth of 1.69-11 GHz and demonstrates good unidirectional radiation patterns over the operating frequency band with peak gain values in the range of 4.13-11.48 dBi.