The Front-End Design Based On Portable Mobile Positioning System

With the development of mobile communication technology, mobile positioning system has attracted more and more attention, which mainly provides services of location queries, peripheral information, map navigation, personnel location and other information, etc. While, when people stays inside the building mobile, the certain height information is very important in the situations such as emergency rescue and tracking criminals. According to engineering practice, the key technology of the mobile positioning have been studied in this thesis.Both two-units and four-units single pulse antenna arrays based on the principle of sum and difference beam together with the broadband feeding network are proposed in this thesis to achieve a wide band operation. The broadband orthogonal directional coupler and phase shifter are both realized by the adoption of the elliptical aperture coupling. To improve the accurate of the positioning, the sum and the difference beams need to be symmetry, wide beam, and the phase center of the antenna array should be coincidence with geometrical center as much as possible. The authors’ contributions are as follow:1. The design of broadband collar-shaped gradient planar monopole-like directional radiation antenna has been done in this thesis, also, the U-shaped ground plane is adopted to modify the radiation pattern. The return loss of the antenna array is greater than 10 d B ranging from 650 MHz to 2175 MHz, which makes it easier to be used across DCS/ PCS/ UMTS/ CDMA/ Wi MAX/ LTE bands. The main factors influencing the bandwidth and the beam width of the antenna have been investigated.2. The authors have made the design of broadband feed network including broadband directional coupler and phase shifter. The broad side coupling is adopted to achieve tight coupling, while the elliptical slot etched in the ground plane is designed to achieve broadband performance. Because of open-to-air structure is adopted, the coupler and the phase shifter are susceptible to the environment. The impact on the S parameters and the phase of the feeding network in metal environment is analyzed. To be applied in engineering, the coupling between the coupler and the phase shifter and the metallic effect have to be eliminated. An access to eliminate the metal influence utilizing proper isolated technique is also proposed and simulated in this thesis.3. The different ways of the antenna array configuration are explored to keep the coincidence with the phase center and the geometrical center of the antenna array. Also,to keep the stability of the phase center is important. The relationship between array configuration and phase center is studied, and the optimized array configuration is given.4. To the system consisting of two antennas, only the simulated results are shown. However, the four antennas system were designed and fabricated. The simulated and measured results shown that the work in this thesis satisfy the simulated results very well, which make them a good prospect of application engineering.