Research on Low Sidelobe Beamforming Algorithm of Cylindrical Conformal Array

‍ ‍Compared with traditional planar phased array radars， cylindrical phased array radars have the advantages of uniformly covering detection performance in all directions and more flexible beam scheduling. However， they suffer from the problem of high sidelobe levels in the pattern. To address this issue， this paper investigates a low sidelobe beamforming method for cylindrical arrays based on the step-by-step synthesis method. By converting the two-dimensional low sidelobe beamforming problem of cylindrical arrays into the problem of synthesizing the low sidelobe patterns of a two-dimensional azimuthally uniform circular （or arc） array and a two-dimensional elevation uniform linear array， the dimensional reduction processing of the two-dimensional low sidelobe beamforming of cylindrical arrays is achieved. This method transforms the low sidelobe beamforming problem of cylindrical arrays into a one-dimensional low sidelobe pattern synthesis problem of a circular （or arc） array. Virtual interference method is a relatively effective low sidelobe beamforming method for conformal arrays， but the existing methods have the problem of ambiguous values for the number of interferences. This paper proposes an improved algorithm for the virtual interference method， which uses the interference sampling ratio to determine the number of virtual interferences， thereby solving the problem of quantifying the selection of interference numbers in the algorithm implementation process. Using the improved algorithm， this paper simulates the low sidelobe pattern synthesis of a one-dimensional azimuthally uniform arc array and the low sidelobe beamforming of a two-dimensional cylindrical array， and quantitatively analyzes the degradation of the two-dimensional beam patterns of the cylindrical array in the azimuth and elevation dimensions when the beam is directed away from the normal direction. The computer simulation results show that within the range of 20° deviation from the normal direction in the azimuth and elevation directions of the cylindrical array beam， the sidelobe levels of the patterns obtained by this method are generally better than -30 dB. Finally， the authors conducted directional pattern testing experiments using a physical prototype of a cylindrical array in a microwave anechoic chamber， and the measured data shows that the sidelobe levels of the patterns in the azimuth and elevation dimensions of the cylindrical array are generally better than -25 dB.