This paper proposes a simple and novel design for breast cancer detection, sizing and localization. A miniature-sized antenna of volume 10 × 10 × 1.6 mm3 is designed at an optimized frequency of 7.98 GHz with a positive gain using the fractal theory; it is based on two nested folds connected to each other using repeated lines, discs and circles. It exhibits a reflection coefficient of -39 dB over a simulated bandwidth of 340 MHz; it has a gain of 1.04 dB and an efficiency of around 70%. This prototype is fabricated and its S11 is measured to get an operational frequency of 8.08 GHz with same S11 and bandwidth values. The insertion of slots in the antenna design improved its performance to get a higher [Formula: see text] of 8.21 GHz and an improved gain of 2.43 dB. The SAR value of the antenna is found to be around 1.4 W/Kg at a safe separation distance of 60 mm from the breast. As an array, it proved its ability to detect the presence of the tumor, its size and position. This is simply achieved by plotting the propagating E-field that is induced inside the breast. The main advantage of this system lies in the fact that it does not require any long-time complicated image processing. By observing E-field plots, it is seen that the | Ex | decreased from 8.37 V/m to 1.91 V/m. As for the | Ey |, it increased from 2.72 V/m to 4.12 V/m; both comparisons made between healthy and cancerous tissues, respectively. Simulations are conducted in HFSS; the antenna proved to be a good candidate for breast tumor detection, sizing and localization systems.