| Global navigation satellite systems (GNSS) is to provide high-quality global positioning, navigation and timing services. With the development of satellite navigation technology, many countries have constructed their own satellite navigation systems. Nowadays, satellite navigation systems are very intensively used. The American GPS and the Russian GLONASS are already operable worldwide. The European Galileo-System and Chinese Compass-System also have provided services partially. Future satellite positioning navigation system will be a compatible mode with multimode satellite navigation systems to improve the positioning accuracy and resolution of a single system covers the blind spot. Terminal antenna is a very important part of the satellite position navigation system. The performance of the system is affected by it partly. So the investigation of terminal antenna for multimode satellite navigation systems is of great practical significance.Multimode satellite navigation antenna is required to cover GPS, GLNOASS, GALILEO and COMPASS systems. Its frequency band is 1164-1615.5MHz, and relative impedance bandwidth is 33%. Its polarization should be RHCP (Right Hand Circular Polarization). The antenna should provide omnidirectional pattern with RHCP wave. So there are two difficulties in the design. The one hand, a wide impedance bandwidth (BW=451.5MHz), on the other hand is a broadband circular polarization bandwidth.This paper analyzes the design requirements of satellite navigation antenna, and then studies microstrip antenna and broadband power-divider phase-shifter network. The main work carried out the following:1. Described the type of microstrip antenna, radiation theory, feed method and analysis method, and then studied the broadband technology and the circular polarization technology of microstrip antenna, simulation examples is given by HFSS. 2. Proposed a novel broadband microstrip antenna structure, four narrow slots have been etched on the radiating patch symmetrically to expand impedance bandwidth, the size and position of narrow slots is analyzed and studied in this paper.3. Studied the basic theory and design method of Wilkinson power divider and Schiffman phase shifter. Proposed a broadband power-divider phase-shifter network to improve circularly polarized bandwidth and circularly polarized purity.This antenna is analyzed and designed by high frequency simulation software HFSS and ADS. Then the antenna is fabricated. It is measured in anechoic chamber. The measured results show that the proposed antenna can achieve 55% impedance bandwidth (S11<-10db), the circularly polarized feature is excellent. The antenna is suitable for GNSS application. |
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