A Study And Design Of The Spiral Antenna And Array Antenna

Nowadays,the information times that people live in is changing greatly. The wireless communication technology is changing every day, whose development is further promoted by the coming of Mobile Communication 4G Times.As one of the most important parts of them,the antenna get the rapid development.During a long time before, the traditional simple antennas have been playing a stable role and serving the wireless communication system.But recently, because of the special requirements of the antenna applying platform, the traditional simple antennas can not meet the practical requirements, and the antennas which has such characteristics as wide-band,circularly polarization and low-profile are greater and greater,so the Archimedean spiral antennas are used widely in the programs. In this article,the Archimedean antenna is studied carefully,major works are summarized in the following aspects:First, a double-arms Archimedean spiral antenna which works in the Frequency of UHF is designed, compared with the traditional ones,whose feeding structure is more simple. The feeding structure that the transformer from micro-strip to parallel-strip is used instead of a balun,which gets the feeding more simple. The simulation results tell us that the antenna has a good match in impendence and characteristic of polarization.Second, a double-arms Archimedean spiral antenna which works in the Frequency of UHF is studied, whose maximum wave direction can transform from axial to cone.The axial beam appears when the arms is excited out of phase,while the conical beam appears when the arms is excited in phase.Third, after the double-arms spiral antennas, a single-arm Archimedean spiral antenna which works in Frequency of S is designed, and it is used as the antenna unit consisting a 24-unit antenna array, and the cross polarization is improved by rotating the antenna unit. The simulation result indicates that the antenna has a higher gain and a better not-circle degree, which matches the requirements of the programs.At last, to isolate the receiver and emission road in phased array, a diplexer which works in Frequency of S is designed, and the micro-strip diplexer is chosen to reducesize and fabrication easily, which achieves the isolation between the receiver and emission.The simulation result indicates its insert loss is below 0.5 d B,the isolation approaches-40 d B.