Research And Design On Phased Array Antenna Systems

With the rapid development of mobile communication technology, the on-the-move communication antenna system has been widely used in various communication fields. The traditional mechanical scanning on-the-move antenna has the characteristics of low tracking accuracy, long reaction time, high prices and high failure rate, which greatly limit its application. How to improve the performance of on-the-move antenna system and reduce the costs are the key researches included in this paper.Phased array antenna is a new electronically controlled beam scanning on-the-move antenna. It is widely used for its own characteristics of rapid beam scanning, high beam pointing accuracy, and easy conformal characteristic. For the phased array antenna, the design of antenna unit, the directional analysis of antenna array, the performance of the phase shifter and the beam control system based on the antenna array are the key techniques in the phased array antenna system. In this paper, the antenna unit, the antenna array, the phase shifters and the beam control system are analyzed and researched. Based on the need of engineering applications, we design a low-cost and miniaturized phased array antenna system. The main contents of this paper are summarized as follows.1) Design of antenna array. According to the loading principle of antenna, and by using metal disc loading method, something is done to get a good match of the antenna unit, and to reduce the height of the antenna, resulting in a low profile, wide bandwidth and circularly polarized helical antenna unit. By adjusting the structure of the antenna array and changing the feeding phase of each antenna unit, the beam scanning is realized, and the antenna is made to have a high gain and good roundness though at a low elevation.2) Design of phase shifter. According to the basic principles of phase shift, various types of phase shift circuits are analysized and compared, and the appropriate phase-shift circuit form is selected for each phase shifting unit. Select switch linear phase shift circuit is selected for 45 degrees and 90 degrees, and reflection-type phase shifter circuit for 180 degrees, which can reduce the phase shift error as much as possible. By selecting an appropriate PIN diode and dielectric plate, the phase shifter can be miniaturized. Meanwhile, by using the isolation method based on plated through-hole for cascaded phase shifting unit, the impact of each shift inter-phase units can be reduced.3) Design of the beam control system. The main function of beam control system is to collect location information of the communication satellite and the antenna carrier. According to the feedback information of the electronic compass about the motion of antenna carrier at a real time, the system control the phase shift value of phase shifter and changing the beam direction of antenna array, which can realize the beam scanning. And based on the actual need, the beam control system can switch between different operating modes, namely, automatic beam tracking mode and rapid beam scan mode.