The effects of finite metallisation thickness and conductivity in microstrip lines

Purpose - The purpose of this paper is to study and discuss the effects of the finite metallisation thickness and conductivity on the properties of microstrip lines. Design/methodology/approach - Effective dielectric constant and attenuation constant of microstrip lines with finite metallization thickness and finite conductivity are analyzed by the method of lines. The experimental results are obtained by using Vector Network Analyzer and the 3680 V Universal Test Fixture of Anritsu. Findings - The strip thickness has a great impact on the attenuation constant of the microstrip lines. The effects can be divided into three parts by the relationship between strip thickness (t) and skindepth (delta). When t < delta, the attenuation constant will decrease rapidly as the strip thickness increase. When delta < t < 2 delta, the attenuation constant still decrease rapidly as the strip thickness increase, but the slope of the curve will be smaller. When 2 delta < t, the effects of the strip thickness will become insignificant and the attenuation constant still decrease slowly as the strip thickness increase. Originality/value - This paper presents some useful principles about the effects of the finite metallization thickness and finite conductivity in microstrip lines. The reasons for these effects are discussed by analyzing the longitudinal electric field distribution in the strip. Finally, some experimental results are given to verify these principles.