Study On Large Angle Scanning Planar Phased Array

The plane phased array with high gain and low sidelobe large angle scanning ability can provide more accurate information in a more timely manner for field search,detection,recognition and tracking in large range.Nowadays,it has good application prospects in military use radar systems and civilian wireless communication systems.Therefore,the research on the large-angle scanning characteristics of planar phased array antennas has important and far-reaching significance.This thesis is combined with practical engineering applications,and take the large-angle scanning phased array as the research object.Based on the direction pattern multiplication theorem and basic scanning principle of phased array,how to enlarge the scanning range of planar phased array from both antenna elements and arrays studied in this paper.In order to realize the research on the large-angle scanning characteristics of the planar phased array in the one-dimensional and two-dimensional directions,two schemes are proposed in this thesis which include:the pattern reconfigurable quasi Yagi microstrip parasitic dipole antenna element for special rotating array and the miniaturized complementary dipole antenna element for the conventional equidistant plane array,The research shows that the two types of antenna elements and their arrays designed can achieve large-angle scanning in both the E plane and the H plane with the characteristics of low gain fluctuation and low sidelobe level.The main contents of the paper include:1.Based on the direction pattern multiplication theorem and the phased array antenna scanning principle,a simple electric basic oscillator antenna element is designed,and the large-angle scanning that can be achieved in the E plane and the H plane by equidistant plane array simulation.During scanning,the sidelobe level is low,but the gain fluctuation is relatively large which can reach 5dB.Then,a parasitic oscillator is designed to broaden the element beamwidth by adding parasitic patches on both sides of the basic oscillator,Similarly,a large-angle scanning can be achieved in both the E plane and the H plane directions by equidistant plane array simulation.The level of the sidelobe is low and the fluctuation of the gain is within 3.5dB during the scanning process.2.A kind of "dual-feed" improved pattern reconfigurable quasi Yagi microstrip parasitic dipole antenna is designed by loading PIN diode switches on the parasitic oscillator structures.This antenna array in the plane can realize two-dimensional and large-angle scanning in the E plane and the H plane directions through a special way of rotating array elements.The simulation results show that main beam of the array can scan to ±70° in the E plane and the H plane directions and the level of sidelobe is low,gain fluctuation is less than 3dB,and the active reflection coefficient of each array element is good during the scanning process.3.A conventional wide beam complementary dipole antenna element is designed and miniaturized.The radiation characteristics of the antenna element are almost unchanged at before and after improvement.Based on this miniaturized complementary dipole antenna element,a large angle scanning of the main beam in the two-dimensional direction of the E plane and the H plane can be achieved by only the conventional equidistance array.During the whole array scanning process,the sidelobe level is low,and the gain fluctuation is small,which is within the range of 3.5dB.