Research on the influence of rainfall on millimeter wave Doppler fuze

The Doppler Effect for MMW fuze has to be discussed in the encounter course between fuze and target. The target Doppler frequency shift (DFS) and amplitude caused by the relative movement between fuze and target are analyzed at 35 and 95 GHz. The relations of the target DFS and amplitude with the approaching distance between fuze and target are given. Based on MMW pulse radar characteristic, the backscattering RCS of volumetric rain medium in interested rainfall area are calculated for the 10 and 100mm/h rainfall rate, at 35 and 95 GHz. The relations of the rain DFS and Doppler clutter amplitude, which are induced by the interested volumetric rain medium around target, with the approaching distance between fuze and the volumetric rain medium are given. The influences of the rain Doppler clutter on target Doppler signal are analyzed. It is shown that with the distance approaching and rainfall increasing the influences become gradually bigger, especially, for a smaller target RCS and a wider fuze radar beam. Therefore, for the MMW Doppler fuze, in order to operate in all-weather environment, when encounter distance is less than about 30m, the influence of the rain Doppler clutter on the target Doppler signal has to be considered.