Optimum transmitter optics aperture for satellite optical communication

An important aspect in satellite optical communication is to obtain minimum bit error rate (BER) using minimum power. This aim can be achieved with very small transmitter beam divergence angles. The disadvantages of too narrow divergence angle is that the transmitter beam may sometimes miss the receiver satellite, due to pointing vibrations. A mathematical model of communication and tracking systems that optimize the BER as function of the transmitter gain is derived.