Various sources of energy are available in the indoor environment such as thermal, light, kinetic or electromagnetic energy to power the wireless devices. The electromagnetic energy can be scavenged from the most ambient sources, even from other wireless devices. In order to collect as much energy as possible, the antenna should work in more than one frequency band. In this article, a triple band antenna based on proximity coupled feeding is proposed. The designed antenna is able to resonate at three frequency bands, 2.45GHz, 5.0GHz and 5.8GHz. The measurement results show that the antenna can not only achieve small size but also high gain in three frequency bands. Consequently, the antenna can be used for RF energy harvesting by combining with the rectifying circuit to supply power for indoor wireless devices.