Design Of Wide-Band Wide Angle Covering Low Side Lobe Array

Modern radar system requires that the detection beam have a small main lobe width,low sidelobe,and can perform frequency hopping in a wide operating bandwidth to reduce the probability of radar detection and interference by hostile forces.Therefore,it is very important to design an array with a narrow-beam lobe,low sidelobe and frequency-hopping broadband.In order to realize the frequency hopping,it is necessary to design a shunt-fed power divider network for the serial feed array method with less loss is no longer applicable.Moreover,it is necessary to design a wide-angle-covered array unit to avoid a decrease in the gain of the antenna during the wide-angle scanning.This paper mainly studies the design work of the shunt-fed power divider network with broadband low sidelobe and completes the design of an X-band 1?16 broadband wide-angle-covered and low-sidelobe array antenna on this basis.The sidelobe level of the designed array is less than-20dB,the width of H surface lobe is up to 120~o and the working bandwidth is2GHz(8.6-10.6GHz).The work done in this paper mainly includes:1.The design of the power splitter that needs to be used in the power divider network is completed.A waveguide with a larger power capacity is selected to design the waveguide ET branch.The ridge waveguide is chosen to design the waveguide coupler so as to make the operating bandwidth of the waveguide coupler meet the design requirements.The narrow side of the ridge waveguide is compressed,a square aperture with a large diameter is selected and the double row non-ridge area is arranged to increase the coupling degree so that the length of the waveguide coupler can be reduced.The waveguide is used to design power splitter to reduce the loss of the power divider network.Branch line couplers with good isolation were chosen as microstrip power divider to reduce the interaction between array elements.The branch line coupler is designed with less-loss stripline to reduce the loss of the microstrip power divider network.2.Completed the design of the array antenna and designed a double-sided vivaldi antenna as the antenna element.This kind of structure realizes the integrated design of the antenna unit and the power divider network on the same substrate.The double-sided design and stripline feeding also reduce the mutual coupling effects between elements,increase the cut-off frequency of the antenna and make the width of the H surface lobe of the antenna element in the design frequency band reach120~o.The array is designed and the influence of coupling on the element pattern is taken into consideration,the antenna element can maintain a wide angular coverage in the array through the optimization of the array spacing,thus the array element spacing of the wide-angle overlay array can be obtained.3.The classical Taylor synthesis method was chosen to synthesize the arrays and the power distribution of the array was calculated by the MATLAB language programme.The resulting power distribution was directly brought into the array pattern function and the designed array feeding to verify the accuracy of the programme.4.Completed the design of the entire power division network.A parallel structure was chosen to design the power divider network in order to realize broadband in-phase output.The connection devices such as standard waveguide-ridge waveguide transition,twisted waveguide,phase compensation structure,and ridge waveguide-stripline conversion are designed for the connection of the power splitters at all levels.The simulation of partition of the power divider network was conducted and the power distribution results were brought into the designed array to verify the design results.