Optimizing time delay of time modulated linear array elements to reduce the side band radiation level

In this paper, a new approach to reduce the side band radiation level of time modulated linear array is presented. Keeping normalized on-time duration of the array elements at each modulation period remains unchanged for a given pattern at fundamental radiation, a suitable time delay is provided before the switch-on instants of the array elements. The method is applied to the pattern where the fundamental radiation is a static Dolph-Tschebyscheff (DT) pattern with SLL of -40dB. The optimum time delay required for the array elements are explored through particle swarm optimization technique and it reduces the maximum of first side band radiation level from -12.7dB to -18.7dB and that of second side band from -17.5 dB to -22.1 dB.