The Study Of High Gain Omnidirectional Circularly Polarized Antenna For Marine Wireless Communication

With the development of marine shipping industry, in order to improve the reliability of the shipping, the requirements to marine wireless communication are becoming more and more demanding. Antenna is designed as the portal of the wireless communication, its performance is determining to the entire system. High gain omnidirectional circularly polarized antenna for marine wireless is meaningful.In marine wireless communication, it's difficult to predict the exact location of mobile ships. So omnidirectional antenna is the first choice for its transmitting and receiving information from every direction. Comparing to the land mobile communication, marine wireless communication is easily deteriorated by climate and seawave. Adopting circularly polarized technique with which multipath interference (MPI) can be suppressed, high performance antenna can be obtained.In the paper, high gain omnidirectional circularly polarized antenna is designed for marine wireless communication. Sleeve dipole is chosen as antenna array element, because of its omnidirectional radiation and its configuration as antenna array. In the array, serial feeding is chosen as the feeding method. By loading parasitically excited antenna element, in the far field we can get a pair of quadrature components, which have the same magnitude, so circularly polarized antenna is readily obtained. Due to the demanding requirements of reliability and performance in the practical environment, the bandwidth is extended to satisfy the requirements of the engineering specification using microstrip matching circuit. The performance of the antenna is verified by simulation and experiment. The data from experiment measurement indicates that antenna gain reaches more than 4dBi, the impedance bandwidth is 150MHz (VSWR＜1.5) and the circularly polarization bandwidth(axial ratio＜3dB) is 90MHz when it operates at its central working frequency(f=2.45GHz). The simulation and test results have good consistency. The antenna features small size, simple and compact structure. Meanwhile it is inexpensive and has practical significance.