Beam pattern synthesis for spaceborne sparse aperture radar

An effective aperture based approach is proposed for the beam pattern synthesis of a sparse aperture array by frequency diversity and post-data processing. The beam pattern by synthesizing signals received by sparse apertures is aliased with many grating lobes caused by undersampling in the effective aperture. To mitigate grating lobes, extra sampling points should add in the effective aperture to improve the sampling period. Two strategies are considered in this paper: first, by frequency diversity on M subapertures, the sampling points can be improved by a factor of M ; second, by synthesizing K pulses on the entire coherent processing integral (CPI) data cube , a synthesized array can be achieved and the sampling points can be improved by K times. With the total MK sampling points improved, the peak sidelobe level (PSL) can be reduced to −25dB with the given parameters. However, the performance is, to some extent, sensitive to position errors. Experimental simulations show the optimized effect.