A Rigourous Dispersive Characterization of Radiating Microstrip Discontinuities and Junctions

A full-wave analysis of microstrip discontinuities in an open environment using integral equations technique solved by the moment method is described. The analysis includes the effects of both longitudinal and transverse current on the strip. Radiation and surface wave effects are included in this analysis. Electric current distributions for a gap microstrip discontinuity and an "L" microstrip junction are presented. Characterization of the discontinuity by an equivalent scattering matrix is then accurately evaluated. from the determination of the current distribution along the lines containing the discontinuities or the junctions under different load conditions. Comparison of results using different number of transverse current cells and different substrate permittivities are also given. Good agreement of our results with those found in the litterature using a spectral-domain analysis is obtained.