Breast cancer is the second deadly cancer for women; for more efficiency and an early detection, the biomedical field need new systems that should be safe, comfortable, and sensible. The medical field already has its methods to detect breast cancer. In this chapter, a new ultra-wide band (UWB) planar antenna is presented for microwave imaging, the antenna is designed to operate in a frequency band from 2.9-10.8GHz. The antenna was designed to be adaptable for multi-viewing imaging due to it simple form, low cost and ease to be manufactured. The simulation results of the new ultra large band antenna and a performance comparison with other UWB antennas. We also offer a circular miniature printed antenna that satisfies the UWB characteristics in terms of bandwidth and reflection coefficient. This antenna is intended for a system for detecting malignant tumors by microwave imaging. The antenna made has a patch on a FR-4 type substrate with εr = 4,3, thickness h =1.575 mm and dimensions ls = 25 mm, and ws = 25 mm. A rectangular slot is inserted on the radiating element ensuring its miniaturization. The latter is powered by a microstrip line width wm with matching impedance at 50 Ohm.