In this presentation we will describe the fundamentals of periodically-loaded transmission-line metamaterials (TL-MTMs) and outline some of their applications . We will begin by analyzing the spatial harmonics excited in left-handed TL-MTMs [2-3]. Based on this analysis we will show how backward waves can be established in TL-MTMs and discuss their homogenization. Subsequently, we will show a model to explain the origin of the broad left-handed bandwidths and low transmission losses characterizing transmission-line metamaterials . Results of the phenomenon of negative refraction of Gaussian beams in left-handed TL-MTMs will be shown to address recent objections raised against the reality of negative refraction . Subsequently, we will present selected applications of transmission-line metamaterials including super-lensing in free space, multi-band and active microwave components, peculiar couplers that support complex waves, and small multi-functional MTM-inspired antennas. Finally and as time permits we will introduce the related concept of the meta-screen and describe its sub-diffraction focusing and imaging properties .
 G.V. Eleftheriades, “EM Transmission-line metamaterials,” Materials Today, vol. 12, pp. 30-41, March 2009.
 M. Zedler and G.V. Eleftheriades, “Spatial harmonics and homogenization of NRI-TL metamaterial structures,” Proc. of the 39th European Microwave Conference, pp. 504-507, Rome, Italy, Sept. 29-Oct. 01, 2009.
 G.V. Eleftheriades, “Transmission-line metamaterials: Theory and Applications”, The Third IEEE Intl. Symposium on Microwave, Antenna, Propagation and EMC Technologies for Wireless Communications, Beijing, China, (4-pages), Oct. 27-29, 2009.
 L. Markley, A.M.H. Wong, Y. Wang and G.V. Eleftheriades, “Spatially shifted beam approach to sub-wavelength focusing,” Physical Review Letters, 101, 113901, Sept. 12, 2008.