High frequency conductor and dielectric losses in shielded microstrip

An integral equation method is developed for calculating the dispersion of imperfectly conducting microstrip lines. Both dielectric losses in the substrate and conductor losses in the strips and ground plane are considered. Multiple conductors on several layers can be studied using an impedance boundary formulation for the derivation of the Green´s function. The microstrip losses are evaluated by using a frequency-dependent surface impedance which is derived by solving the fields in the conductors. This surface impedance replaces the conducting strip and takes into account the thickness and skin effect of the strip at high frequencies. Phase constant and attenuation for single and coupled strips are presented. Good agreement with data available in the literature is shown.<>