We describe a course on the propagation of electromagnetic waves that is built around a problem-based learning (PBL) problem. The paper will describe how the problem was integrated into a pre-existing course that was perceived as highly successful (and hence not apparently in need of enhancement) by linking theory with experiment. The problem involves possible methods of searching remotely for leaks in water pipelines crossing a desert region by comparing the dielectric constant of wet and dry sand at various frequencies. The potentially wide-ranging learning objectives are restricted to the various properties of the reflection of plane waves at interfaces. Even so, any one PBL group can carry out only a small subset of the possible experiments in the allotted time. Thus, an interesting feature of the problem is that the reason that the experiments do not appear to give results with textbook accuracy can only be discovered by cooperation amongst the groups. This gives an added focus to the group presentations.