The Research Of Antennas Applied In Maritime Satellite Communication System Terminal

The fourth-generation maritime satellite broadband communication is a global satellite mobile communications system, which is built by INMARSAT. It provides global users on the sea, or on the earth, or in the sky with secure and reliable voice and internet access services, and compatible with the 3G communication. Fleet Broadband is the name of the fourth-generation maritime satellite broadband communication that appling on the sea. It can provide users with speeds up to 432kbps for mobile broadband services using a very compact user terminal and a sample operation mode. Antenna of its terminal equipment radiates right-hand circularly polarized wave. Its receiving and sending frequencies are 1525-1559 MHz and 1626.5-1660.5 MHz respectively.With a lot of advantages such as compact structure, low profile, easy to implement circularly polarized, microstrip antenna enduring popularity in antenna design field. Now, microstrip antenna has been widely used in satellite communication, radar and a variety of wireless communication devices. This paper is set in Fleet Broadband system. Research and analysis about microstrip antenna for wideband and circular polarization technology have been conducted based on previous studies. Several broadband circularly polarized microstrip antennas were designed for Fleet Broadband portable mobile terminal. The author's main works are as follow:(1) It describes the basic theory, characteristic parameters and analysis methods of microstrip antenna. It gives a detail to the key technologies of circularly polarized and broadband microstrip antenna, and then some feeding networks are studied.(2) Accroding to the characteristics of fleet broadband communication, an antenna structure for Fleet Broadband FB250 terminal was proposed based on the analysis and research of the single-fed circularly polarized microstrip antenna and sequential rotation arrays technology. The antenna was carried out by simulation and experimental validation. The measured results show that the antenna has good CP radiation characteristic with its VSWR less than 1.2, Gain higher than 12dBi, Axial Ratio less than 1.6dB,3dB wide angle axial ratio more than 40°and half power beam width more than 40°over INMARSAT working band. The antenna has many characteristic such as high gain, light weight, compact structure and suitable for portability and mobility.(3) An antenna structure for Fleet Broadband FB150 terminal was proposed based on the analysis and research of the unequal power four-fed circularly polarized microstrip antenna and stacked corner truncated technology. The antenna was carried out by simulation and experimental validation. The measured results show that the antenna has good CP radiation characteristic with its VSWR less than 1.2, Gain higher than 9dBi, Axial Ratio less than 1.6dB,3dB wide angle axial ratio more than 70°and half power beam width more than 55°over INMARSAT working band. The proposed antenna has a low-cost, easy-farbrication, and etc. It provides a practical transceiver for Fleet Broadband satellite communication terminals.