Poly-phase coded waveform design with expanded mainlobe width

Poly-phase coded waveform design with low sidelobe level is an important issue. The sidelobe level of a poly-phase coded waveform achieved by a waveform design algorithm often depends on the degrees of freedom available for optimization. In this paper, we introduce a concept to exploit more degrees of freedom for a given pulse time duration, by allowing for more codes inside whereas keeping a low range resolution. Based on this concept, a waveform design criterion, which is a minimax optimization problem, is proposed. The optimization problem is solved by the least-pth algorithm which uses the L-BFGS as its sub-algorithm. Numerical results show that the additional degrees of freedom can decrease the peak sidelobe level of polyphase coded waveform from -32.6dB for 64 codes to -37.0dB for 256 codes with the same range resolution and pulse width.