TABLE OF CONTENTS The ideal radar absorber would be thin, light, durable, easily applied, inexpensive, and have broadband frequency coverage. As an alternative, we might wish to have a structural RAM that is mechanically sound and has no size, weight, or cost penalty over standard structural materials. As might be expected, neither of these ideal RAM types has yet been formulated. Nevertheless, since World War II (the Germans developed a magnetic RAM paint during the war and used it to reduce the RCS of submarine conning towers), a significant amount of effort has been invested in the development of absorbers that are practical for military applications.
To illustrate absorber design and performance, RAM types that are in widespread use are described and their properties are analyzed. Although the emphasis is on broadband absorbers, the descriptions start with simple, narrowband, single-layer absorbers, which form the components for multilayer broadband absorbers. An underlying assumption in the treatment provided is that RAM volume is a constraint. Therefore, little attention is given to the design of RAM for anechoic chambers and other similar applications, although those types of absorbers are briefly described as examples of geometric transition RAM and are described in more detail in Chapter 13.
Two of the oldest and simplest types of absorbers are represented by Salisbury screens and Dallenbach layers. The Salisbury screen [5] is a resonant absorber created by placing a resistive sheet on a low dielectric...
