Mathematical modeling of a microstrip line with a side screen

Based on the electrodynamic model of a shielded microstrip line constructed by the projection method using the "Chebyshev" basis, the dependence of the slowing down factor and the line wave resistance on the distance of the strip conductor to the side screen is investigated. Simple formulas are obtained for calculating the slowing down factor and the line wave resistance in the quasi-static approximation. The distance from the edge of the strip conductor to the side screen is determined, at which the error in the product of the slowing down factor and the line wave resistance does not exceed 1% compared to a similar product for an open line. The influence of the substrate permittivity on the product of the main electrodynamic parameters of the line is investigated and a simple formula is proposed for calculating the wave resistance at any value of the substrate permittivity.