This work presents a modified Antipodal Vivaldi Antenna (AVA) designed for microwave and millimeter wave imaging applications. First the AVA is designed as reference. Then to obtain high gain at lower frequency, corrugations are added, followed by dielectric lens, metamaterial slabs and a dielectric cavity to improve the gain at higher frequencies to make the antenna desirable for microwave and millimeter wave imaging applications. The proposed structure demonstrates simulated return loss of > 10 dB over 2.2 - 50 GHz with a peak gain of 19 dBi at 32 GHz. © 2021 IEEE.