A few years ago, a new theory for producing coherent Smith-Purcell radiation from an initially continuous electron beam was proposed. It was 2-D, and it has been supported by particle-in-cell code simulations, although no experiments have, until now, provided confirmation. In fact, all experiments used a round beam, for which the 2-D theory may not be valid. We report here on a two-pronged attack on this problem. A 3-D simulation in the microwave domain indicates that coherent radiation, at a frequency near that of the 2-D simulation, should be produced. We are also preparing a demonstration experiment using an intense finite-width sheet beam to confirm the theory and simulations.