| With the continuous development of modern military technology and the application of new generation communication technology,the application of active phased array antenna(APAA)is expanding.The array scale is expanding to meet the needs of modern military equipment and communication equipment for APAA.There is a lot of room for the development of APAA,and the usage scenarios for APAA are increasing.In practical use,due to the gravity,wind,thermal load,the array will inevitably be deformed,which will affect the electrical performance of the antenna.Therefore,it is necessary to accurately evaluate and compensate the electrical performance changes of the array.In order to calculate the far field of large APAA,the electromechanical coupling model is established by using the subarray extrapolation method,which can accurately calculate the far field of the array in the undeformed state and the deformed state;At the same time,in view of the influence of array deformation on the electrical performance of the antenna,considering that the attenuator and phase shifter are discrete inputs in practical engineering,phase optimization compensation and amplitude phase optimization compensation methods are proposed to compensate the electrical performance of the antenna after surface deformation.The research content of this thesis mainly includes the following three aspects.(1)Electromechanical coupling modeling of large active phased array based on subarray extrapolation.Firstly,by analyzing the influence of array element offset on the far-field of linear array and area array,it is clear that the influence of array element offset on the farfield of array can not be ignored.Then,the far-field calculation model of electromechanical coupling is established by using subarray extrapolation method,and the far-field of largescale APAA under ideal array and array deformation is calculated.Finally,a microstrip antenna is used to determine the size of the small array through analysis and simulation.(2)Phase optimization compensation considering quantization error.The traditional phase compensation method only compensates a certain point,and the calculated ideal compensation phase is continuous phase,which can not be directly used in practical engineering.In order to solve this problem,firstly,the ideal compensation phase is quantified by using the phase shift constraint of phase shifter in practical engineering.Then,taking several important indexes such as beam direction and sidelobe level as optimization objectives,the quantization phase is optimized by genetic algorithm to obtain the compensation phase that can be used in practical engineering.Finally,simulation examples and experiments are used to verify the effectiveness of the method.(3)Optimal compensation of amplitude and phase based on best approximation method.Different from single point phase compensation,the best approximation method uses the deformation pattern and ideal pattern of the array surface for overall approximation,which can effectively compensate the whole far field.Firstly,the ideal far field and the deformed far field of the array are used for overall approximation to obtain the best ideal compensation excitation,including excitation amplitude and excitation phase.Then,the discrete input characteristics of attenuator and phase shifter in practical engineering are used to quantify the actual compensation value.Finally,the ideal compensation excitation amplitude and phase are optimized by genetic algorithm,and the compensation excitation amplitude and phase which can be used in practical engineering are obtained.Through the same simulation and experimental cases as in Chapter 3,the effectiveness of this method is verified. |
