A multiport admittance/impedance matrix for the truncated 2D periodic structure is derived via expansion of node voltages and currents in terms of Floquet`s waves. It is shown that for uniaxial propagation, the structure comprised of a finite number of columns/rows is identical to multicoupled lines with properly defined parameters. The 4x4 unit cell array fed at different sides is analyzed using the developed formulation. The results are then verified with a rigorous Sonnet simulation, thereby confirming the validity of the presented approac
