Field emitters are used as distributed electron sources in applications such as field emission displays (FEDs). Reducing the angular aperture of the electron beam increases the resolution and luminance of the FED. This study comparatively analyzes the focusing properties of several kinds of dual-gate emitter structures. The configurations considered are the coplanar and coaxial gate types, and also the coaxial gates structure with protruding emitter, considered for the first time in this context. The simulation work was performed using the SLMION 3D 7.0 software package. Several conclusions are drawn concerning the suitability of double-gated emitter structures for electron beam focusing.