A novel triple band planar antenna using a four-stub-loaded ring-slot on the ground and a U-slot on the microstrip-fed line is presented. The ring slot is designed to drive two different resonant modes, and the four T-shaped stubs are loaded to lower these two resonant frequencies. Moreover, a U-shaped slot etched on the microstrip feeding line is to excite a third upper frequency band without increasing the overall size of the antenna. The computational analysis and measurement illustrate that the proposed antenna can cover three frequency bands of 2.4, 3.5, and 5.8 GHz with good return losses and stable radiation patterns.