| The satellite navigation positioning system, initiated in the United States, has already been widely applied in both military and civilian areas. Antenna, as an important part to transmit and receive signals in the navigation system, is facing more challenges because of changing demands. Based on an actual project as background, this paper proposed the implementation diagram for receiving antenna in a satellite positioning navigation system from the point of theoretical analysis and software simulation. The main issues discussed include the following three aspects:Part I: Element antenna design. From the theory of circular polarization microstrip antenna design, two kinds of element antennas are proposed which are simple and high-gain, including A-type single-fed antenna and B-type single-fed antenna. These two kinds of antenna are compared in the terms of size, VSWR, gain and polarization axial ratio by the simulation software CST. B-type single-fed antenna is chosen as the element antenna as the unit of the array designed for the project. In the working frequency 2.49175GHz, B-type antenna element's gain is 7.8dB at the size of 37.6×36.09mm2. Its right-handed gain is 14dB larger than left-handed circular polarization gain and its 6dB axial ratio angle is about 170°.Part II: Antenna array design. In this part, the formation of array and the different method to feed are discussed. Two kinds of formation are presented: the 1×8 linear array and the 2×4 plane array. These two kinds are studied by simulation software in terms of size of whole structure, antenna array gain, polarization axial ratio and so on. The 2×4 plane array is fabricated and measured by E8363B vector network analyzer. From the measure results, in 2.47~2.52GHz band the VSWR is less than 1.5:1. The maximum gain in E-plane pattern is 15.8dB and its 3dB pattern width is 18°. The maximum gain in H-plane pattern is 15.6dB and its 3dB pattern width is 42°. The measure results completely meet the requirement of project and it proves the correctness of the design method.Part III: The design of the feed network. The design theory and method of microstrip power divider is discussed and an one-to-eight power divider with three degrees of one-to-two divider is designed by simulation software ADS and CST. It is fabricated and measured by vector network analyzer E8363B. In the 2.44GHz~2.54GHz band, its VSWR is less than 1.1:1. Its insertion loss S21 is less than 9.3dB and its isolation degree S23 is between -22~ -26dB. The measure results show the power divider designed is low-return-loss, low-insertion-loss, high-isolation degree and meets the project requirement completely. |
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