Beam-scanning performance of a slot array antenna on a composite right/left-handed waveguide

The spread of metamaterial concepts has lead to the appearance of waveguides with a composite right/left-handed (CRLH) behavior, i.e., supporting both forward and backward waves, together with a zero-phase-constant wave. The use of this kind of waveguide as feeding structures gives rise to a new generation of slot array antennas, which exhibits new radiation capabilities, such as backward-to-forward beam steering. Although this new feature has been widely proven on simple prototypes -like the long-slot leaky-wave antenna-, it has not yet been explored with more-complex slot arrays. The object of this paper is to examine the scanning performance offered by a slot array antenna on a CRLH waveguide. A six-slot array has been designed, constructed and measured. Some brief guidelines to tackle the design are given. The far-field simulations are in good agreement with measurements, confirming not only the new radiation possibilities offered, but also the the validity of the design procedure used.