Slow Wave Theory
Slow waves refer to the propagation of electromagnetic waves with phase velocity much smaller than the speed of light, c . This wave behavior can be achieved by changing the constitutive (e,ju) parameters of the medium properties. Of course, the traditional way is to load the medium with appropriate dielectric properties. But, this is an expensive and cumbersome process and often implies use of exotic and low loss materials, not available in practice. Thus, engineering techniques and synthetic materials need to be considered to realize slow wave phenomena. These techniques often involve the construction of periodic stacks of dielectric layers for the goal to emulate the behavior of artificial dielectrics. The concept of metamaterial is based on periodic structures and leads to engineered media with unusual properties. Indeed, periodic media have received considerable attention due to their usefulness in dispersion engineering. In this section, we introduce the concept of slow wave propagation using periodic loading of CTLs followed by experimental demonstration.