ABSTRACT
This chapter provides an analysis of coupled transmission lines (CTLs) that are loaded with (L, C) elements in a periodic manner. Slow waves refer to the propagation of electromagnetic waves with phase velocity much smaller than the speed of light, c. Periodic stacks of dielectric material arrangements are often called photonic crystals. They support waves that exhibit multiple reflections as they propagate through photonic crystals. The chapter derives a circuit model of CTLs and discusses its dispersion behavior using a simple second-order dispersion. The magnetic photonic crystals (MPC) dispersion and related wave slowdown have been used for RF antenna miniaturization, bandwidth enhancements, and for photonics applications. The operation of Traveling Wave Tubes (TWTs) is based on the Cherenkov radiation and involves the coupling of an electron beam to an RF wave. Antenna miniaturization is a desirable property in antenna engineering. Reduction in antenna dimensions helps accommodate small mobile devices, such as smartphones and portable transceivers.
