Design of Dual Band Circular Polarization Stacked Microstrip Antenna for GPS Applications

In this paper dual-band microstrip antenna for Global Positioning System (GPS) application is designed.This design contents on two circular patch ( upper circular patch, lower circular patch) printed on a two-layer substrate of an FR4 dielectric layer, and cutting a crossed-slot in the upper patch and four I slots in the lower patch. The antenna can work at GPS Ll band (1.575GHz) and L2 band (1.227GHz). The design achieved an approximately impedance bandwidth of 15.8 MHz for L1 for two ports, while L2 band is 11.8 MHz for two ports with maximum gain of 2.54dBi and 1.177dBi in the L1 and L2 band respectively for two ports. The resulting circular polarization (with axial ratio ≤ 3 dB) has been found to meet that required for this application. The VSWR is approximately1.1  (VSWR ≤ 2) for L1 and 1.2 for L2. Results were obtained above using the software CST, which shows that this antenna can meet the demands of the signals of satellite navigation system.The antenna dimensions are (70*70 mm 2 ). The structure is compact and has a good application prospect. The results with low-profile characteristics make the antenna suitable for GPS applications. Keywords: microstrip antenna, GPS antenna, Circular polarization, dual-band antenna, Global Positioning System.