Array Antenna Sensitivity Analysis And Tolerance Design Based On Electromechanical Coupling

Since the advent of array antenna,it has been widely used in the fields of communications,radar and other fields due to its strong orientation,beam shaping,and easy implementation of phased scanning of beams.However,as an electronic device,array antenna will inevitably face the process of array processing and array installation.The random error of array element position is inevitable,but it seriously affects the performance of antenna.With the development of array antennas towards high frequency bands,high gain,and low side lobes,the more strict requirements are put forward to the tolerance of the random error of the array element position.So how to quantitatively analysis the electromechanical coupling to the array antenna,how to rationally design the array element's position tolerance to ensure that the array antenna can meet the requirements of increasingly harsh electrical performance is very important.At the same time,as a most widely used antenna array,the radar antenna is developing toward the direction of stealth.The change of the scattering performance index such as stealth drives the array antenna to break the traditional full design method and innovate toward the sparse array.Therefore,what is the coupling relationship between the array element position error and the radiation field and the scattering field,how to arrange the sparse array's elements so that it can realize the requirement of reducing scattering field's lobe value,how to solve the problem that traditional excitation current weighting cannot reduce the side lobe of sparse array antenna,how to reasonably allocate the array element position tolerances to resist the deterioration of radiation and scattering performance,all of these problems are waiting to be solved urgently.Thus,in this paper,the following work was performed on array antennas:A new tolerance design method which can improve the electrical performance of the antenna is studied.Considering that the location errors of different elements and the location errors of each element in different directions have different effects on the electrical performance,the concept of sensitivity is applied to array antennas.First,based on the calculation formula of the electrical performance of the array antenna,the sensitivity calculation model of the electric field and the direction coefficient to each element position is derived.Then,apply the sensitivity calculation model to a rectangular grid array antenna and the sensitivity of the electric field and direction coefficient of the antenna to different array elements is calculated.The calculation results show that the maximum sensitivity of the electric field intensity and the directional coefficient to the array element located at the center of the array is greater than that of the element located at the edge,and the sensitivity to the Z direction of the array is much larger than that of the X and Y directions.Finally,based on the sensitivity distribution of the maximum coefficient of the directional coefficient of the array antenna for different element locations,a method for determining the position error tolerance of the array element based on the array sensitivity is designed.Through a case study,it is shown that compared with the common tolerance calculation method,the proposed method can reduce the maximum side lobe lift of the radiation field by 1.013 d B and can reduce the maximum RCS of the scattered field by 1.5d Bsm.In order to improve the stealth performance of radar antenna,the sparse array antenna is selected as the research object.First,the structural error is introduced into the analysis of the radiation and scattering properties of the sparse array antenna,and the electromechanical coupling model of the radiated and scattered fields is deduced,and then the arrangement of sparse array antenna array elements is designed based on the two coupling models,making the side lobe levels of the scattered and radiated fields can be reduced at the same time.Then,these two electromechanical coupling models are used to analyze the influence of the array element position random error on the electrical performance of the sparse array antenna,and the tolerance value of the array element of the sparse array antenna is designed by using the traditional tolerance calculation method.Subsequently,aiming at the fact that the traditional excitation current weighting method cannot be applied to reduce the side lobe of the sparse array antenna,a genetic algorithm based excitation current amplitude weighting method is designed.Finally,the sensitivity of the electrical performance of the sparse array antenna is calculated by the finite difference method,and the array element position tolerance is designed according to the sensitivity.The calculation results show that the design method based on sensitivity is not only able to reduce the maximum side lobe lift of the radiation field by 1.863 d B,but also reduce the maximum RCS of the scattered field by 0.688 d Bsm.In order to make it easier and quicker for antenna designers to use this method for antenna tolerance design,two tolerance design software used for array antennas are designed.By using these software,array position tolerance can be quickly calculated and the electrical performance changes with respect to the position error relative to no error are obtained.It can also make electromagnetic design for sparse array antenna,get the array layout and excitation current weighted value that satisfies the requirements,and provide reference for antenna designers quickly.And make sure that these two software can provide theoretical reference for antenna structure and electromagnetic designers.