The constant frequency pulse trains of Radar can produce the high peak sidelobes. Stepped frequency signal is used to reduce these lobes with wider overall bandwidth while having small instantaneous bandwidth. For uniform frequency stepped pulse trains, there can be undesirable peaks of the autocorrelation function, known as grating lobes, around the main lobe. In this paper we address this issue, using an approach which allows us to suppress grating lobes. The stepped frequency signals with linear modulation are used. In order to maintain the sidelodes minimum along with grating lobes, we also analysed the Non linear frequency modulation.