In this paper, an asymmetric coplanar waveguide with a single-finite ground plane is presented. Three infinite-thin metallic plates are excited in the even mode. The left-side finite ground plane is similar to a strip, and the right-side ground plane is an infinite ground plane. There are four parameters including two-gap width and two-strip width that can be controlled. Utilizing the conformal mapping techniques, the calculated results have a good agreement with full-wave simulation about the electric properties with respect to the structural parameters. It is suitable for a practical 50 line, a high-impedance line, and transition designs.