Research On Wide-angle Scanning Phased Array Antenna Based On Mode Theory

Because of the flexible control of the beam and the well capability of anti-interference,the phased array systems have been applied to the civilian and military areas widely,which gradually replace the traditional way of mechanical rotation control.For the antenna part of the phased array systems,the focus of research has gradually shifted to the research of planar phased array.However,the scanning range of traditional microstrip phased array antenna is limited,which seriously restricts the development of phased array.In recent years,expanding the scanning range and effective working bandwidth of phased array has become a hot research topic.Based on the mode theory of microstrip patch antenna,this thesis studies the problem of wide-angle scanning of phased array antenna and expanding its effective bandwidth through the design of array elements.The main contents are as follows.The first chapter mainly summarizes the research background and significance of this paper,and summarizes the research status of phased array antennas to expand the scanning range and broadening bandwidth.Finally,the subsequent paper chapters are arranged;The second chapter mainly describes the mode theory of microstrip antennas and the beam-scanning mechanism of phased array antennas.For example,the mode theory,field distribution and radiation pattern of the modes of the conventional rectangular microstrip patch.The working principle of the phased array antenna is described later.This chapter provides a theoretical basis for the subsequent design of broadband,wide-angle scanning phased arrays.In the third chapter,a wide-beam element is constructed based on TM₂₀ mode of rectangular patch.Because of the high-order mode of patch,the size of antenna element is larger than half-wavelength.According to the current distribution of the element,a certain miniaturization technology is adopted to construct a scanning phased array based on this element,which realizes one-dimensional wide-angle scanning and effectively expands the scanning range.Besides,metal columns are added between the units to ensure better isolation between the units.Then,based on the complementarity of different patches'different modes,the rectangular patches'TM₁₀ and TM₀₁ mode and circular patch's TM₂₁ patches are combined to realize the complementarity of the pattern,and a joint wide-beam element is constructed.Based on this element,the array achieves two-dimensional wide-angle scanning.The prototype is tested and the results are in good agreement with the simulation results.In the fourth chapter,based on different modes of waveguide structure,the working bandwidth of antenna element is extended by mixing the two modes.At the same time,the substrate integrated waveguide structure effectively ensures the isolation of antenna elements during the scanning process,and ensures the effective working bandwidth during the scanning process.Within the working bandwidth range,the radiation efficiency of the array is guaranteed to be 70%.The final chapter summarizes the above work of this paper,and puts forward to the development direction of phased array antenna in the future.