Designs Of Dual-band CNSS Antennas And Complex Dual-polarized Antennas For Base Station

Chinese Compass Navigation Satellite System (CNSS) has independentintellectual property rights. In order to meet the uplink and downlink bands of thesystem, a dual-band circularly polarized (CP) antenna should be developed andapplied. Meanwhile, due to the small number of CNSS satellites, the high gain ofterminal antenna for low elevation is required.The third generation mobile communication system (3G) has been officiallyimplemented in our commercial. With the increasing complexity of the system, it isurgently need to solve the multipath fading and reduce the number, the cost and thelocation of antennas. For just meeting these requirements, the compositedual-polarized base station antenna has been the future trend.In this dissertation, first, a recent work about circularly polarized or compositedual-polarized base station antennas would be introduced. Second, how to achievemulti-band or wide beam properties for the CP antennas would be presented andanalyzed. At the same time, some design methods for the dual-band oscillator andantenna array would be discussed. Last, it is need to introduce the theories aboutdual-band oscillator and microstrip antenna, and as well as the antenna parameters.This paper gives emphasis to the design of CNSS circularly polarized antennasand the composite dual-polarized base station antennas. Several antennas aredesigned as follows so as to provide practice support:1. A novel compact circularly-polarized antenna with spiral slots for CNSSdual-band applications is present. The antenna structure is simple and easy to process.In addition, it can largely reduce the size of the antenna and meet the some speciallyminiaturization requirements.2. Two designs of wide beam circularly-polarized antennas are present. It isobserved that the beam of the CP antenna can be effectively widened by loading aparasitic radiation ring or four parasitic metal cylinders.3. A composite dual-polarized base station antenna is present. The antenna has acompact size, low VSWR and high isolation characteristics. Although some patternindicators do not meet the requirements, it could be put into commercial.