| In recent years, high-precision satellite navigation terminal units, used ingeography and engineering measurements, is begetting more and more attentionbecause of their accuracy, high speech, cheep and easy operation. The high-precisionmeasurement antenna is an important part in such high-precision terminal systems. Theantenna phase center variations and multi-path effect would lead to serious error in themeasurement. So study of high performance measurement antenna has a positivemeaning to the application of satellite navigation systems.In this dissertation, the demand of satellite navigation measurement antenna andseveral antenna forms are analyzed, and the effects brought in by antenna are studied.The phase center, axial ratio, pattern and Gain of the planar slot spiral antenna areanalyzed using Ansoft HFSS software. An optimize method is carried out to improvethe performance of antenna’s axial ratio. Furthermore, real antennas are produced aswell as simulation and design; the measurement results show that the antennas couldmeet the requirements of the navigation system.The thesis is organized as follow three parts:(1) The recent developments of measurement antenna and the key research fieldsare introduced. The forms and performances of several common antennas used in thecurrent navigation systems are analyzed.(2) The study focus on planar slot spiral antenna used in satellite navigationmeasure system. Firstly, important parameters required in analysis, such as matchingresistor at end of feed line, spiral gap length, reflecting cavity depth, medium plateradius and feeder width, are determined by the means of studying the antenna’s structure.Secondly, theoretical analysis of impacts on antenna’s performance caused byparameters is undertaken. Computational simulation using Ansoft HFSS software is alsotaken to summarize the characteristics of the impact brought by the changing of theseparameters. Finally, according to the results obtained, a four-arm slot spiral antenna isdesigned. The real antenna is produced and the performances are measured. Themeasure results show that the antenna pattern, the gain of low elevation angle and thestability of phase center meet the requirements of a measurement antenna, but theperformance of axial ratio is relatively bad, with more than3dB on the radiationorientation in the range of45, it need to improve.(3) The causations of the impact on antenna axial ratio performance of plane slotspiral are studied. Based on the structure of antenna feed part. Against to the defect ofthe method which using phase shift and power divider, the method which is usinguneven width circular feeder is be raised. The simulation results show that methodwhich using uneven width circular feeder can improve the axial ratio performance, and it does not change other performances of the antenna. Finally a real antenna is producedwhich according to simulation result of the method, the measurement shows that thevalue of the axial ratio reduce to blow3dB in the radiation direction in the range of45, while other performance is not changed. The method’s availability and feasibilityare illuminated. |
PDF Full Text Request