A Compact CPW-FED Monopole Antenna with Triple Bands for WLAN/Wimax Applications

A novel compact coplanar waveguide (CPW)-fed printed antenna with triple bands for WLAN and WiMAX applications is presented. By using a parasitic circular patch, a pair of symmetrical inverted-L strips and a 50-Ω transformer, the antenna can effectively provide a good input impedance matching. The tuning effects of the ground size, the parasitic circular patch and the symmetrical inverted-L strips to the resonance and matching condition are then examined, and the prototype of the proposed antenna is further fabricated and measured. The experimental and numerical results exhibit that the antenna has impedance bandwidth for ≤-10 dB of 2.32-2.80 GHz, 3.06-4.13 GHz and 5.03-6.04 GHz, which can cover both the WLAN 2.4/5.2/5.8 GHz bands and the WiMAX 2.5/3.5/5.5 GHz bands. Also, a stable monopole-like radiation pattern and an average antenna gain of 3.06 dBi across the operating bands have been obtained.