Double-Polarization Slotted Phased Array Antenna Based On Single Ridged Waveguide

The phased array antenna system of weather radar is one of the hot research fields at home and abroad,which has the characteristics of multipolarization,large scanning Angle and high resolution.The thesis aims to study and design the row element antennas with the narrow-wall inclined slots of rectangular waveguide and the broad-wall longitudinal slots of the single-ridged waveguide,and the two row elements are arranged to form a dual-polarized phased-array antenna with a large scanning angle.The main contents of the thesis are as follows:First,the relevant theories of waveguide and waveguide slot antennas are briefly introduced,and the normalized equivalent conductance theories of the broad-wall longitudinal slots and narrow-wall inclined slots of rectangular waveguides are described in detail,and the principle of the beam scanning of phased array antennas is briefly described.They provide a theoretical basis for the scheme of the dual-polarized phased-array antenna in this thesis.Secondly,based on the slot theory of rectangular waveguide and a computer-aided method,a horizontally polarized row element with a length of 2.5 m and narrow-wall inclined slots of rectangular waveguide is designed and verified by the CST simulation software.The horizontal beam width of the row element antenna doesn't exceed 1°.The gain is above25 d Bi,and the first sidelobe level is better than-35 d Bi.The simulation results fully meet the design requirements.Then the physical processing and testing of the antenna are performed,and the test results are consistent with the simulation.According to the requirements of the gain and the beam width of the array antenna,the 64 row elements are arranged at a certain distance to form the required array antenna.And then the array antenna is processed and tested in physical form.The gain of the array antenna is greater than 41 d Bi,and the beam width does not exceed 1.8°,and the first sidelobe level is better than-32 d B.The test results fully meet the design requirements,verify the feasibility of the scheme,and provide a template for the design of dual-polarized phased-array antenna.After that,a single-ridged waveguide with broad-wall slots is used to design a vertically polarized row element antenna with a length of 1.5m according to the indexes.The keystep is that the gap conductance function is extracted in a computer-aided design method and then the gap conductance distribution is obtained based on Taylor weighting,and finally the specific position of each gap is obtained.The antenna model is simulated,and the gain is higher than 19 d Bi,the horizontal beam width is not more than 2.3°,and the sidelobe level is less than-35 d B.The simulation results verify the feasibility of the scheme.Finally,according to the requirements of the dual-polarized phased-array antenna,the broad-wall slots array of a single-ridged waveguide to radiate vertical polarization and the narrow-wall slots array of non-standard rectangular waveguide to radiate horizontal polarization,as the row elements,are arranged to form a dual-polarized antenna.For the requirements of the gain,beam width and scanning angle of phased-array antenna,16 row elements with broad-wall longitudinal slots of single-ridged waveguide and 16 row elements with narrow-wall inclined slots of rectangular waveguide and a horizontal length of 1.5m are alternately arranged in order to form the dual-polarized phased-array antenna with a large scanning angle.The antenna model is simulated,and the gain is more than30 d Bi.The beam width in the horizontal direction is less than 8°,and the beam width in the vertical direction is less than 3°,both the sidelobes in the horizontal and vertical directions are less than-30 d B when antenna scanning is not performed.The beam scanning characteristics of the antenna are simulated,and different amplitudes and phases are set for each excitation port,so that the scanning angle in the elevation reaches ± 50°.And the simulation results are consistent with the design specifications of the antenna.It has the advantages of compact structure and low sidelobe level.