Research On Wide Beam Antenna Unit And Its Technology In Wide-angle Scaning Phased Array Antenna

The phased array antenna is composed of many unit antennas.The unit antennas stimulate different feeding phases to change the beam direction of the entire phased array antenna and realize the beam scanning.In order to solve the problem of two-dimensional circularly polarized array wide-angle scanning,this paper starts from the basic theory of the antenna,based on the principle of using a wide beam unit to expand the scanning range of the phased array,and researches and designs two different types of antenna units according to the subject requirements.These two wide beam units are applied to different types of arrays.In addition,a double-circularly polarized wide-beam circularly polarized unit for large-scale arrays is also designed.The main contents are as follows:First,the background,development trends and principles of the phased array antenna are introduced.The design steps and key technologies of the wide-angle scanning phased array antenna and wide beam antenna are summarized,which provides a theoretical basis for the subsequent comprehensive design.Secondly,a wide-beam unit with a microstrip structure is designed,which uses the cut-off effect of the metal cavity on the entire radiation field to widen the beam width of the antenna.The wide beam unit is designed into linear polarization and circular polarization forms respectively.For the linear polarization unit to form a linear array,a wide-angle scanning of ± 82° in a one-dimensional linear phased array is realized.According to the actual requirements of the subject,the circularly polarized wide beam units are arranged in a rectangular arrangement to form a two-dimensional array to realize the circularly polarized scanning of the two-dimensional 16-element array,which can realize the scanning of ± 57° in the two-dimensional plane.After processing and testing,the design requirements were basically achieved.Thirdly,a wide-beam circularly polarized antenna in the form of a single-arm spiral is designed,and the beam width of the single-arm spiral is also extended through a metal cavity.The broadband impedance matching of the spiral antenna is realized by adopting a coneshaped structure.The wide-beam single-arm spiral unit is composed of a 19-element array arranged in a triangular grid,and the array units at different positions are rotated at different angles to obtain good circular polarization characteristics.Because the scanning ranges of the two planes are inconsistent,it can be verified by simulation that one plane can achieve ± 47° scanning and the other plane can achieve ± 53° scanning.Finally,according to the previously designed microstrip circularly polarized wide-beam unit,a wide-beam circularly polarized unit with double circular polarization applied to a largescale array is designed.Two types of double-circular polarization feed network are designed,which are a four-point feed network combined with a double-point feed network in the form of a 3d B branch line coupler and a 3d B branch line coupler and T-shaped power splitter.The two feed networks were applied to the double-layer microstrip antennas respectively,and the processing and testing showed that the results were in good agreement with the simulation results,and the four-point feed form network solved the problem of cross-polarization deterioration.Finally,an array element with unequal beam width is designed,and the unequal beam width of different planes is realized by constructing a special-shaped structure.