ABSTRACT
This chapter presents an overview of some of the radiating devices and both leaky-wave and resonant-type radiation structures and antennas. Composite right-/left-handed (CRLH) metamaterials have lead to several breakthroughs in both one-dimensional and two-dimensional leaky-wave antenna and reflector applications. A leaky-wave antenna is an antenna whose radiation is produced by a traveling wave progressively leaking out power as it propagates along the antenna structure, which operates as a leaky waveguide. CRLH metamaterial leaky-wave antennas overcome the limitations of conventional leaky-wave antennas and therefore render leaky-wave antennas practically useful, competitive with other antenna solutions, and even superior to prior state-of-the-art antennas in several respects. As many applications require fixed-frequency operation for effective channelizing, scanning by varying frequency may be impractical. In the case of electronically controlled CRLH structures, one other functionality is available in addition to beam scanning. The chapter also presents an efficient CRLH pencil-beam antenna that provides distinct advantages in terms of simplicity and flexibility over conventional-phased arrays.
