The dc properties of a periodic focusing system consisting of a parallel pair of ladder lines, together with focusing plates parallel to the lines, are calculated. First, Laplace's equation is solved in an approximate way; following this, the paraxial‐ray equation for an electron sheet beam, injected into the system halfway between the ladder lines, is solved for perveance, plasma frequency, beam stiffness, and average beam potential. Finally, a numerical example is presented and discussed.