Rapidly converging direct singular integral-equation techniques in the analysis of open microstrip lines on layered substrates

In this paper, moment-method-oriented direct singular integral-equation techniques are used for the exact analysis of planar layered microstrip lines. While these techniques retain the simplicity of the conventional method of moments, they optimize them by evaluating all matrix elements via rapidly converging real-axis spectral integrals. The proposed algorithms yield highly accurate results for the dispersion characteristics and for the modal currents both of the fundamental and higher order modes.