Comments on “Complex Impedance Transformers Consisting of Only Transmission-Line Sections”

Summary form only given. In the above-named work [ibid., vol. 60, no. 7, pp. 2073,2084, Jul. 2012], the problem of impedance matching using one transmission line of characteristic impedance Z_c and electrical length θ, inserted between two impedances, Z_L = R_L + jX_L and Z_S = R_S + jX_S, is analyzed. In the same paper, the allowed regions for impedances Z_L which may be transformed into real impedance Z is a complex impedance, an analysis on a few numerical results is presented, but the allowed regions for Z_L are not specified on the Smith chart. In this Letter, based on the analysis of the condition to obtain a real number for Z_c, it is shown that the allowed regions for Z_L when Z_S is a complex impedance may be displayed on the Smith chart, too.