Closed form expression for conductor loss of asymmetrical CPW lines

The symmetrical CPW is a popular structure in the MMIC technology as all conductors are coplanar that does not require any via to approach the ground. The asymmetrical CPW (ACPW) shown in Fig.1 provides additional degree of freedom to control the line characteristic. Several analytical methods [1-2], closed- form expressions [3-4] and experimental investigations [5-6] have been reported to compute the conductor loss of the symmetrical CPW. For the case of microstrip line, Lee and Itoh [8] presented the phenomenological loss equivalence method. Heinrich [9] also presented a circuit model for this purpose applicable to the symmetrical CPW. Holloway and Kuester used the concept of 'stopping distance' to compute the conductor loss of microstrip, symmetrical CPW, symmetrical CPS etc. [4, 10, 11]. This method is accurate and applicable to both the thick and thin strip conductors. However, they have not used the method to compute the conductor loss of asymmetrical CPW (ACPW).