Abstract:A triple-band microstrip antenna is designed using the characteristic of a microstrip ring antenna. The proposed antenna consists of a 1/8(45°) ring antenna, a ring slot in the center and an array of shorting-pins placed on the edge of the patch. The slot and the shorting-pins in the patch can excite three resonant frequencies and decrease the physical size of the proposed antenna. The influences of those additional structures on the performance are studied. And the triple-band antenna is designed based on the studies. There is a good agreement between the experiment results and the simulation results. The proposed antenna can operate at 0.9 GHz, 1.8 GHz and 2.4 GHz with operating bandwidth of 7 MHz,12 MHz and 20 MHz,respectively. Their measured gain are about 4 dBi,5 dBi and 6 dBi,respectively.