Effectiveness assessment of null-on-transmit

The Georgia Tech Research Institute (GTRI) has performed an assessment of the effectiveness of null-on-transmit (NOT) techniques for a generic, phased array, radar antenna. Our objective was to evaluate potential NOT techniques, presented by Steyskal (1982, 1983) for minimizing the effects of jammers at known locations. Initially, an approach employing small phase-only perturbations (PO-NOT) was examined. PO-NOT would be attractive since phase perturbations would be relatively easy and inexpensive to implement in a phased array antenna. Using computer simulations, we quantified the effectiveness and limitations of PO-NOT. Due to resulting limitations on the effectiveness of PO-NOT, we then conducted an effectiveness assessment of NOT using amplitude and phase perturbations (A/P-NOT). Although being more complex and costly to implement, the A/P-NOT technique was found to eliminate many of the limitations which exist with PO-NOT.