Scintillation of aperture received partially coherent beams with time-averaging detection in turbulent atmosphere

A general scintillation index model for time-averaging reception of partially coherent beams (PCBs) is extended from the case of point receiver to the case of aperture receiver. The analytic expression is derived including the effects of the receiver aperture diameter D  , the correlation time τSτS of the source phase variation and the integration time τDτD of the detector. There exists a maximum value τmaxτmax of the relative detection speed (RDS) τS/τDτS/τD. When the RDS is lower than τmaxτmax, the PCB can reduce the scintillation compared with the coherent beam. An approximated expression for τmaxτmax is derived, which is useful for making choice of the detector speed under different link conditions. It is also found that under the influence of finite RDS, increasing receiver aperture size can degrade the performance of the PCB in scintillation reduction, compared with the coherent beam in weak turbulence regime.