It is important to distinguish the sideband intensities of individual crystallites, sk, and a rotoraveraged one sk 2 . The individual sideband amplitude sk is complex and its phase varies widely among the crystallites as a function of rotor angle. The rotor-angle averaged sideband intensity equals to sk 2 , which is smaller and absorptive . The phase spread of sk plays a key role for the effective rf field and the spin dynamics for pulses lasting a rotor-period or longer. The mean magnitude of the sk can be estimated from the number of ssbs within the span of satellitetransition frequency ~1.5νQ, of which νQ is the quadrupolar coupling frequency, and the