Compensation Method For Electrical Performance Of Active Phased Array Antenna For Structural Error

Active Phased Array Antenna(APAA) has been widely used in various radar systems, because of its’ unparalleled advantages in high reliability, multi-function, high detection, strong tracking capability and good stealth performance. The fabrication and assembly process of the APAA structure will bring random error on array surface; when the antenna works, vibration, shock and heat consumption will cause distortion of the APAA structure. Random error and structure distortion of the APAA structure will bring the antenna element’s position errors, and then cause deterioration of the electrical performance of the antenna. Therefore we need to compensate the electrical performance of the APAA. Based on the APAA electromechanical coupling theory, without considering the unit pattern and the mutual coupling between array element, this paper has analyzed the principle and process of three kinds of compensation method for the electrical performance of APAA, respectively are phase adjustment, amplitude and phase adjustment based on least squares method, amplitude and phase adjustment based on FFT method,ant then compared and studied their compensation result. This paper mainly includes the following aspects:Firstly, this paper has introduced the APAA structure-electromagnetic coupling model, and then analysis the influence on antenna electrical performance caused by the structure error with this coupling model to find out the error boundary beyond which we need to compensate the electrical performance of the APAA.Secondly, this paper has discussed the compensation principal and compensation result of those three method based on the APAA electromechanical coupling theory.(1)Phase adjustment method: we calculate the additional phase error caused by element position errors with the APAA electromechanical coupling model at first, and then adjust the phase of excitation current to offset the additional phase error, after that we can compensate the electrical performance of the antenna. From the result of examples, we can see that phase adjustment method do well in compensating the beam pointing error.(2)Amplitude and phase adjustment based on least squares method: we establish the ideal pattern’s expression and error pattern’s expression of the antenna with the APAAelectromechanical coupling model, based on the least squares method. And then set the excitation current in error pattern as unknown variable, the least squares solution which makes the difference between the ideal pattern and error pattern minimum is the compensation excitation current. From the results of examples, we can see that amplitude and phase adjustment based on least squares do well in compensating the gain, sidelobe and beam pointing error.(3)Amplitude and phase adjustment based on FFT method: this paper established the Fourier transform relationship between antenna pattern and the excitation current combined with the application of FFT in the calculation of the antenna’s pattern. Then converted the structure error to the excitation current, and adjust the amplitude and phase of the excitation current to compensate the electrical performance of the antenna. From the results of examples, we can see that amplitude and phase adjustment based on FFT do good in compensating the gain, sidelobe and beam pointing error.Finally, compare the scope of those three compensation methods in this paper, and summarize the full contents of the text and propose the research prospects in next step.