The Design And Fabrication Of A Microstrip Antenna For BGAN System

International Maritime Satellite is a mobile satellite communication system of global geostationary earth orbit, which can provide voice and data service for global users on the sea, or on the earth, or in the sky. Recently, Broadband Global Area Network (BGAN) system was established by transport communication center of Chinese ministry of Communications. Its receiving and sending frequencies are 1525-1559 MHz and 1626.5-1660.5 MHz respectively. In order to receiving and sending signals by using the same antenna, the working band of the candidate antenna should be 1525-1660.5 MHz, Its relative band width should be 8.5%.Microstrip antennas are good choices for BGAN system, because they have some principal advantages, such as small size, light weight, low profile and so on. But the frequency band of a single microstrip patch antenna is only about 0.7%-7% usually, which obviously cannot satisfy the bandwidth request of the BGAN system. Therefore, the key points of this article lie in the studies and grasps of the broadband technology of microstrip antennas, and applies them to the terminal antenna design of the BGAN system.In recent years, there have been lots of researchers devoted to the study of broaden the bandwidth of microstrip antennas, and have made very big progress. But, the related references indicated that, nowadays, the systematic design methods for broadband microstrip antennas are still not pefect. The methods for microstrip antennas' bandwidth broaden are mainly tried to find out by experiments. After the study and summarize of massive related literatures of microstrip antennas, this article provides a detailed design of the terminal array antenna for the BGAN system. In this design, the structure of the array element antenna uses dual-point feeds, circularly polarized , dual layers microstrip form, makes use of the foam which has low price, low dielectric permittivity as the medium materials, to reduce the cost and broaden the impedance bandwidth of the antenna; In foundation of the dual-layer structure, combining with capacitive coupled feed technology, the impedance bandwidth of the microstrip antenna has been further expanded; Using the designed array element structure to compose a 2x2 microstrip array antenna, and designs a reasonable feeding network, thus enhanced the antenna gain.In this paper, first, we will calculate the antenna dimension parameters in transmission line Method. Next, we will simulate and optimize this kind of antenna with electromagnetic simulation software Ansoft HFSS, which has good reputation in electromagnetic field. Finally, we will fabricate and test that antenna, give some parameters and compare to simulation results.The simulation and measured results shows that this antenna has good wideband characteristic. The impedance bandwith for VSWR<1.5 in the entire bandwith of BGAN system, and more than 13dB gain is achieved. It meets the demands of the BGAN system.