Recently, built-in printed antennas for handset applications are increasingly in demand due to the flexibility for industrial design and low-cost fabrication. In this paper, a printed antenna is proposed by using an L-shape radiating element and an open-loop resonator to achieve multi-operation bands, including GSM900/DCS1800 and WLAN2450 or Bluetooth system.. The antenna is fabricated with a FR-4 substrate. The HFSS FEM-based 3-D full-wave EM solver is used for the design simulation. The simulation and measurement results of the input VSWR, input impedance, radiation patterns, and power gain are presented, compared, and discussed.