Optimal number of phased array faces for horizon and volume surveillance revisited

The problem of the optimal number of phased array faces for performing both horizon and volume surveillance over 360 degrees is revisited. Previously, assuming the detection performance is the same in all beam positions and the total number of T/R modules is constant, it was shown that for either horizon or volume surveillance, the optimal number of array faces was three. This was true whether the arrays were operating simultaneously or sequentially. In this paper a more realistic scan loss is used and the effects of fill pulses for pulse-Doppler waveforms are considered. It is shown that for array faces operating simultaneously, as the required clutter fill increases, the optimal number of array faces grows from three to four for both horizon surveillance and volume surveillance. For equal performance, the fill is about 50 km for horizon surveillance and in excess of 200 km for volume surveillance. However, the four-face systems may require additional electronics and an additional signal processor; and this needs to be taken into account.