Wave Field Synthesis (WFS) is a physical based sound reproduction technique. It relies on linear arrays of regularly spaced omnidirectional loudspeakers. A fundamental limitation of WFS is that the synthesis remains correct only up to a corner frequency referred to as spatial aliasing frequency. This paper addresses irregular spacing of loudspeaker array for WFS. Adapted driving functions are defined. New formulations of the spatial aliasing frequency are proposed. It is shown that the use of logarithmically spaced loudspeaker arrays can significantly increase the spatial aliasing frequency for non focused virtual sources.