UMTS (Universal Mobile Telecommunications System) technology is one of the third-generation (3G
) cell phone
technologies, which is also being developed into a 4G
technology. Although UMTS2001 is the most widely-deployed UMTS band, some countries utilize 1900 MHz instead. Besides, the co-existing GPS (Global Positioning System) operates at the frequency of 1575 MHz. Thus, a desirable antenna in UMTS systems needs to cover both of two bands in order to operate in various devices. This paper will propound an antenna covering the range of frequencies from 1.53 GHz to 2.53 GHz that includes 1.575 GHz, 1.8 GHz, 1.9 GHz ,and 2.1 GHz. The developed quasi-Yagi antenna has a simple-low profile and achieves a bandwidth of 48%, a front- to- back ratio of 19 dB, a gain of 6dBi, and an efficiency of better than 78% at 2.1GHz. In this paper, the study on effects of parameters of the antenna is also investigated to achieve optimal model.