The first of the truly 'modern' engines, the AMD is a hungry but powerful beast.
Matter and Anti-matter are mixed in minute quantities in a shielded chamber which gives off a veritable cornucopia of energy which is used to create and manipulate gravity fields around the vessel.
These fields can be aligned to 'pull' the ship forward at high speed. This has many advantages over the older means of propulsion most notably not requiring a specific engine 'exhaust', and allowing the ship to move in any direction at will.