By coupling a stub-loaded open-loop resonator onto the back of a CPW-fed mirrored-L monopole, a novel triple-band planar antenna has been achieved and is presented. The proposed antenna features a compact structure with reasonable gains. The measured bandwidths for the distinct triple-band are 2.27-2.87-GHz, 3.4-4.15-GHz and 5.11-6.7-GHz. Omnidirectional radiation patterns for the three bands are observed. Simulations are confirmed by the experimental results, which ensure that the proposed antenna is well suited for WiFi and WiMAX applications.