Calculation of characteristic impedance of transmission lines with substrate integrated artificial dielectric structures

A calculation method for the characteristic impedance of transmission lines with any perturbation structure is proposed. An analytical procedure is described with proper equations based on simple transmission line theories. The obtained characteristic impedance by the proposed method shows an almost constant value, while it fluctuates severely depending on the frequency in the conventional method. As a sample transmission line element, a microstrip line with the substrate integrated artificial dielectric (SIAD) structure is selected for calculating the characteristic impedance by the proposed method. The calculated characteristic impedances from the simulated and measured S-parameters well converge to a constant value without fluctuation.