Research On Beamforming Based On Virtual Array Technology

The technology of virtual antenna expansion can expand the aperture of array antenna and increase the resolution of angle in the virtual sense under the condition of quantitative array antenna size.Moreover,the virtual extension technology can improve the degree of freedom of array antenna,so that a large number of signals can be processed by a relatively small number of array elements.In this thesis,a robust beam-forming method based on conjugate virtual array and a dual-function radar anti-interference method based on side-lobe cancellation and zero broadening are studied.The main research work of this paper can be summarized into the following two parts:(1)In order to solve the problem to improve the performance of array antenna beam,a method of signal steering vector expansion based on conjugate virtual array is proposed.By using conjugate virtual elements to expand the array,the aperture of the array is increased,without change the actual number of array elements,and the side-lobe level is reduced,and the manufacturing cost of the antenna would not be increased.Based on the virtual array,the steering vector of the signal is extended to make the beam-forming effect of the array more robust.Through the simulation of 11 array elements with or without interference and amplitude and phase errors,the original array beam,virtual array beam and extended steering vector beam are analyzed and compared,and the effectiveness of the above method is verified.(2)In order to improve the stability of the anti-interference performance of the array antenna,a null broadening method based on the side-lobe cancellation algorithm is proposed.Two side-lobe cancellers are used to realize the communication function of the dual function radar antenna in both active mode and static mode,and the interference can be effectively suppressed in both modes.Then,the null broadening method is introduced,so that the null of the interference point can be broadened in both modes,and the interference can be well suppressed when the interference fluctuates in a certain range,then the stability of anti-interference performance of array antenna is increased.Through the simulation of 11 element array antennas,the effectiveness of the above method is verified by analyzing and comparing the array beams with side-lobe cancellation algorithm and several beams with zero-collapse broadening.