The equivalent admittance of a 2-D array of printed metallic patches/apertures is obtained here by extending a precedent equivalent circuit approach reported by some of the authors. The goal of the present extension is to cover more complex situations like multi-resonant scatterers, several scatterers per unit cell, and conical incidence. After studying the limits of validity of the equivalent circuit approach, it is found that this quasi closed-form approach is a very efficient numerical tool which also provides a very convenient physical insight into the involved electromagnetic phenomena.