Closed form expression for conductor loss of conductor backed asymmetric coplanar waveguides

We present closed-form expression to compute the conductor loss of the conductor backed asymmetric coplanar waveguide (ACPW). The expression is based on the perturbation method and the concept of the stopping distance. The effect of the presence of the conductor backing on the loss computation is discussed. Comparisons with the method of moment based software LINPAR are presented to validate the expressions derived for the asymmetric case. The analytical characterization presented in the paper is well suited for inclusion into CAD codes for MMIC design.