This work presents the miniaturization of a single rectangular microstrip antenna at 2.45 GHz in the ISM “Industrial Scientific and Medical” band by using the fractal technique. This microstrip antenna has A CPW fed and designed for RFID reader system on FR4 substrate with dielectric constant of 4.4, and simulated performing CST Microwave Studio. The total area of the final circuit is 21.22 × 32.05 mm².The validated antenna has a good matching input impedance range from 2.304 GHz to 2.625 GHz with a stable radiation pattern, a loss return equal to −35.9 dB, and a gain of 2.2 dBi.