Presented is a portion of a research project which developed materials for teaching remote sensing of natural resources on an interdisciplinary basis at the graduate level. This volume contains notes developed for a course in active remote sensing. It is concerned with those methods or systems which generate the electromagnetic energy "illuminating" the target or resource to be detected. It attempts to provide guidance in the development of theories to support experimental results, and to bring together information useful to both the engineer and the resource manager. A primary aim of the course is to train students to use their own judgment about the value of a remote sensing system for a particular application. The notes include a short course in electromagnetics and a review of electromagnetic properties of natural materials. These tools are used to study the interaction between natural resource targets and the electromagnetic energy from active systems. Typical images and other types of data are examined to understand experimental results. (Author)