The degradation of cancellation performance by frequency variations in adaptive weights

An attempt is made to set limits on the relative frequency variations of adaptive weights in an adaptive MBA (multi-beam antenna) system so that 40 dB of interference cancellation are obtained. Using simple expressions for the relative amplitude and phase variations, the cancellation performance of the system is calculated as a function of the scale factors of the variations in amplitude and phase. For worst-case variations, the linear ramp can be at most +or-1.0% across the bandwidth, and the ripple about +or-2.5%; the linear and quadratic phase variations can amount to +or-1.5% an +or-2.25%, respectively, at most. More realistic cases permit the relaxation of these constraints by a factor of 2-4.<>