Wireless communication is one of the most blooming areas in the communication field today. The increasing number of wireless standards and device technology improvements are placing a high demand for multiband antennas. In this paper, the authors propose a dual band bowtie antenna with C shaped defective ground structure and slot on the radiating surface. The antenna exhibits an improved reflection coefficient at frequencies of 1.5GHz as well as 4.5GHz. The defective structure helps decreasing the resonant frequencies without increasing the overall size of the antenna. The antenna can be used in GPS as well as INSAT applications.