ABSTRACT
In this chapter, we will review recent research progress on radio-
frequency (RF) and microwave beam-forming techniques using
planar metamaterials and metamaterial surfaces (metasurfaces).
This chapter starts with discussions of principles and physics
of guided-and leaky-wave characteristics of periodic planar
structures, such as transmission-line-basedmetamaterials, followed
by their active versions that enable novel smart antennas with
beam-steering functions. We include detailed descriptions of their
practical realizations and the integration with active elements and
circuits, which enables adaptively tailoring electromagnetic waves.
We clarify a wide variety of planar metamaterial-/metasurface-
based beam-forming techniques, giving a critical assessment and
comparative analysis in the RF and microwave bands. These
techniques, which are ideally low cost, low profile, and fully
integratedwithmonolithic circuits, will offer promising applications
in modern wireless communication, radar, remote sensing, and
medical and security imaging.
