A method for obtaining dispersion characteristics of shielded microstrip lines

An equivalent network representation is presented for the analysis of dispersion characteristics of shielded microstrip lines, with particular attention directed toward the effects of waveguide cross-sectional geometry. The effective dielectric constants and characteristic impedances of microstrip lines are obtained to illustrate the effects of the size of the waveguide cross section. The method is based on a building-block approach to microwave network theory, using the rigorous mode-matching technique to solve the boundary-value problem. The approach offers many advantages: the problem is formulated in a rigorous fashion, with both TE and TM modes of each constituent region included to account for the hybrid nature of the guided modes. The treatment of a complicated boundary-value problem is reduced to one of a simple junction discontinuity. The analytical results so obtained are simple in form, and clear for establishing physical concepts associated with the microstrip lines. Numerical results obtained are shown to be in good agreement with available data in the literature.<>