Motivation: Breast cancer is a major health problem globally for women causing an appreciable percentage of the yearly female death. Microwave imaging is a promising method in biomedical applications such as breast cancer detection due to its good penetration property, non-ionizing and non-invasive nature which has the potential to be a complementary modality to standard mammography. In this paper, An UWB Microstrip-fed Vivaldi antenna for microwave imaging systems aimed for an early breast cancer detection is developed.