Study of two scatterer interference with a polarimetric FM/CW radar

The coherence zone for a single photon, which is related to the range resolution for a radar, is defined in terms of physical optics and the uncertainty principle. Two scatterers located approximately within this zone give rise to interference in the scattered wavefield. In this paper, the two-scatterer interference profiles measured with a 45 GHz FM/CW radar are studied. Downrange translations of one scatterer with respect to another for a distance of lambda/4 produces a phase shift of pi which alters the line shapes from constructive to destructive interference. In a computer simulation, the backscattered wave from each scatterer is modeled by a sin X/X-type function with associated amplitude and phase. Excellent agreement with measured data is obtained. The resolution conditions for two coherent scatterers have been analyzed in detail.