AbstractIn this study, fast and new analytical formulations have been presented for correct loss calculations in asymmetrical coplanar waveguides (CPW) with finite‐extent ground planes for CPW mode. To generalize loss analysis for CPW mode, not only gaps but also finite ground planes are assumed as asymmetric. Moreover, dielectric thickness and ground plane widths are considered as finite for this transmission line. Another important concept presented in this article is that the proposed expressions are easily applicable for CAD platforms. Through the analyses, conformal mapping techniques (CMT) have been employed. The obtained results in this work have been compared with the results of other similar studies (spectral domain method, mode matching, etc.) available in the literature. These comparisons indicate that the expressions developed in this study are found to be more suitable for accurate calculations of loss as well as the characterization of asymmetrical CPW with finite‐extent ground planes. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2082–2087, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22709