Altair VHF/UHF observations of multipath and backscatter enhancement

During the US Defense Nuclear Agency´s PEAK (Propagation Effects Assessment-Kwajalein) experiment, Altair, a high-performance long-range VHF/UHF tracking radar, was used to track spherical satellites in low-Earth orbit. The experimental results are used to demonstrate an enhancement, due to scattering, in the average received power that is observed during severe scintillation. This enhancement is predictable on the basis of the first-order amplitude statistics for two-way radar propagation in monostatic propagation geometry as well as by a more thorough analysis using reciprocity. Both analytic approaches are presented. The enhancement is important for both ground- and space-based radars that have to operate during scintillation, since as much as a 3-dB increase in the target (and clutter) signal-to-noise ratio is possible, depending on the severity of the scintillation and on the radar transmit/receive geometry