It is shown that with appropriate multimode illumination and modulation strategies, it is possible to achieve the high sensitivity of active illumination, with the elimination of the need for “strategic” angular orientation of the target and to do so while minimizing the impact of coherent effects such as speckle. It is also shown that very modest terahertz (THz) power levels correspond to very high brightness temperatures, even when this power is divided among the many modes of large enclosures. We also consider how technical advances in the THz will continue to expand the scenarios of applicability for these approaches.