Research On Antenna Technologh For Satcom-on-the-move Versus Phased Array

In recent years, the technology of SATCOM-ON-THE-MOVE has developed rapidly and it plays an important part in market of satellite communication field. As the name suggests, the biggest advantage of SATCOM-ON-THE-MOVE is that it can communicate when the platform is moving include cars, ships and other In cars, ships and other fast-moving platforms. Traditional SATCOM-ON-THE-MOVE antenna can basically be divided into three categories:High profile, medium profile and low profile antennas. Among them, low profile antennas have the advantage of less windage resistance, small volume and low power consumption which make them a hot research direction in SATCOM-ON-THE-MOVE field.Low profile SATCOM-ON-THE-MOVE antennas include shaped reflector antenna, flat plate antenna, phased array and so on. Phased array has the ability of fast beam scanning and it can transport information stably on fast moving formats. But phased array is not widely used in market due to it’s complexity and high cost. Shaped reflector is currently used as a more mature low profile SATCOM-ON-THE-MOVE antenna. Therefore, the research on phased array meets the market demand and has a lot of research space.According to the current market demand, a phased array which can be used in the SATCOM-ON-THE-MOVE system is designed in this thesis. As to the selection of antenna element, this paper utilizes microstrip antenna which has the advantage of low profile and less windage resisitance. Two different microstrip circular polarization units are designed and simulated by CST software. Simulation results show that the two microstrip circular polarization units can both work in the 8GHz to 9GHz band with ±45 degree half power beam width. In the half power beam width, the axial ratio is less than 3d B. The difference between the two elements is one for single circular polarization and the other one is dual circularly polarized radiation and the single circularly polarized radiation gain is higher than the other one. The single circular polarization microstrip antenna is used as the basic unit of phased array, and then array scheme is deeply analyzed. The result shows that contrasts to conventional array-arrangement, periodic rotation of array antenna can reduce the axial ratio and improve the ability of circular polarization radiation effectively. Accordingly 12×12 array is designed and studied in detail. The result shows that the gain of the array is26.7dB whose error less than 0.4d B compared to theoretical calculation. The array can reach 45 degrees beam scanning in azimuth and elevation, while the gain of array decreases during the scanning process but it still meets the requirements of technical specifications. Monopulse direction-finding can be used in this array whose null depth is-40 d B. Based on the previous results, 168×168 elements array is simulated by software and the radiation performance can meet basic requirements of technical specifications. In addition, the instantaneous bandwidth of SATCOM-ON-THE-MOVE system is discussed. Two important factors that influence the instantaneous bandwidth of phased array are analyzed and a solution to the project is presented.