Large format focal plane arrays (FPAs) of lenses are promising candidates for wide field of view sub-millimeter imagers. Recently, a spectral technique based on coherent Fourier Optics has been proposed for analyzing such lens based FPAs in reception to facilitate the optimization via a field matching with the lens feed pattern. Based on this technique, three practical lens antenna geometries based on silicon, quartz and plastic lenses combined with leaky-wave antenna feeds are proposed and compared here. The synthesized lens based FPAs achieved scan loss lower than standard horn based FPAs, leading to wider field of views.