A SIMPLE METHOD FOR SEPARATING BISSIPATION FACTORS IN MICROWAVE PRINTED-CIRCUIT BOARDS

A simple method for separating the dissipation factors associated with both conductor losses and dielectric losses of printed circuit boards in microwave frequencies is presented. This method utilizes the diffe rence in dependence of two dissipation factors on the dimensions of bo unded stripline resonators using a single printed circuit board specim en as a center strip conductor. In this method, the separation is made through a procedure involving the comparison of the measured values o f the total dissipation factor with those numerically calculated for t he resonators. A method, which is based on a TEM wave approximation an d uses Green's function and a variational principle, is used for the n umerical calculation. Both effective conductivity for three kinds of i ndustrial copper conductor supported with a substrate of polyimide fil m and dielectric loss tangent of the substrates are determined using t his method from the values of the unloaded Q measured at the 10 GHz re gion. Radiation losses from the resonator affecting the accuracy of th e separation are discussed, as well as the values of the effective con ductivity of metals on the polyimide substrate which is calculated usi ng the above method. The resulting values of the effective conductivit y agree with those using the triplateline method within 10%.