A modified tri-band CPW-fed antenna is designed on a PCBoard with ²r = 4.4 for RFID applications. The design is optimized to operate at 0.915 GHz, 2.45 GHz, 3.50 GHz using the finite element method. In this design, two U-shaped branches are added as additional resonators to achieve multi-band operation based on our previous design. Simulation shows that the 30 × 30 mm2 antenna achieves less than −10 dB return loss at the targeted frequencies. Fur- thermore, the antenna achieves less than −8 dB of S11 at 5.8 GHz. Simulated current distribution and radiation patterns are given in the paper.