A dual-band full-space scanning leaky-wave antenna based on a ferrite-loaded open waveguide structure is proposed. The lowest three bands of this structure are: the composite right/left-handed (CRLH) mode with positive group velocity first reported recently, the traditional isolator edge-guided mode, and a mixed forward/backward perturbed waveguide mode with a negative group velocity in its leaky-wave region. The leaky-wave regions of the CRLH and of perturbed waveguide modes are exploited to provide dual-band radiation. Due to their opposite group velocities, the two modes have their ports placed at both ends of the structure, which allows independent matching sections and also avoids the necessity of a diplexer. The antenna was demonstrated by both full-wave simulation and by experiment.