| The wideband array antenna are studied in this thesis,the mainly content is as follows:1.Combining with the requirements of engineering project,a wideband dipole array antenna with beam scanning function is studied.The Marchand balun is improved,and the designed feed structure achieves third-order impedance matching,which effectively broadens the bandwidth of the dipole antenna.Full-wave simulation analysis of the antenna is carried out in the HFSS software,and its equivalent circuit model is verified by the joint simulation of HFSS and ADS.The designed antenna has an impedance bandwidth of 72.7%(1.27-2.72GHz)when VSWR<2 and a pattern bandwidth of 50%(1.2-2 GHz).The antenna is also fabricated,and the test results have the same bandwidth.On this basis,the infinite periodic structure is used to simulate the infinite array.The beam scanning capability and the change of antenna bandwidth with the distance between elements is simulated.The beam scanning performance of the array on the E-plane is better than that on the H-plane.Then the finite 4-element linear array and 16-element planar array are simulated and analyzed.The simulation results show that the 1×4 linear array can achieve±30°beam scanning on the E-plane in the range of 1.54-2.68 GHz(relative bandwidth is 54%),and the 4×4 planar array can also achieve±30°beam scanning on the E-plane in the range of 1.4-2.3 GHz(relative bandwidth is 48.7%).2.The wideband characteristics of tightly coupled array antenna fed by a compact wideband integrated balun are studied.The dipole antenna is used as the array element,and the coupling capacitance is generated by the antenna arms stacked on each other to expand the array bandwidth.Based on the principle of marchand balun,a miniaturized integrated balun composed of two asymmetric stacked spiral transmission lines is designed,with a matching bandwidth up to ten octaves.The equivalent circuit model of the antenna is given,the size of the antenna is optimized in ADS,and the antenna element is simulated in HFSS.In order to eliminate the short-circuit point at the high frequency,a resistive frequency selection surface is introduced.In addition,a short-circuit sheet is introduced between the antenna arm and the ground plate to reduce the matching deterioration when scanning on the E side.The element has a bandwidth of 8.4:1(0.75-6.3 GHz)under the condition of VSWR<3,and can realize±30°beam scanning on the E-plane and H-plane.The profile height is only 0.07?low.The method of extending the edge element antenna wall is used to cut the edge of the finite array,and the bandwidth along with phase scanning characteristics of 1×8 linear array are simulated and analyzed.It can be seen from the simulation results that the array has a bandwidth of 4.24:1(2.1-8.9 GHz),and can achieve±30°beam scanning on the E plane. |
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