We present strong and weak Finite Element Method formulations for 2D closed electrostatic problems. Special hierarchical higher (arbitrary) order basis functions are applied. Results for characteristic impedance of shielded planar transmission lines, obtained by the two formulations are compared with results from the literature, and their specific advantages briefly commented. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1114–1119, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25917