With the continuous growth of wireless communication service and the constant miniaturization of communication equipment, there are higher and higher demands for the small volume of antennas, integration and working band. So in recent years, great interest was focused on microstrip antennas for their small volumes, low profiles, good integration, low cost and good performance. The rapid progress in wireless communication requires the development of light weight, low-profile, flush-mounted and single-feed antennas. Also, it is highly desirable to integrate several RF modules for different frequencies into one piece of equipment. Hence, multi-band antennas that can be used simultaneously in different standards. Particularly, the multi-slot structure is a versatile approach for multi-band and broadband design. Also, feeding these structures could be simpler by using suitable points to slot techniques for different slots. WLAN has made rapid progress and there are several IEEE standards already, namely 802.11a, b, g, y and n, used the bands of 2.4, 3.5 and 5.2 (GHz). In this book a triple band circularly polarized microstrip patch antenna for wireless network applications is presented.