This paper studies the class of nonuniformly spaced planar arrays in which the elements are located on a lattice derivable from a conformal mapping of a uniform lattice. The array space factor is formulated in a two-dimensional Poisson's sum. The grating plateaux are determined from a stationary-phase integration. An optimization process is applied to make the grating plateaux flat. The array derived is the conformal exponentially spaced array having characteristics very similar to those of the linear exponentially spaced array. A numerical example is included to justify the various approximations used in the analysis.