An Analytical Model to Approximate the Radiation Conductance of Microstrip Gaps

This paper presents an analytical model for the radiation of microstrip gap discontinuities based on existing models for open-ended microstrip lines. Contrary to previous publications, the model presented does not require general full-wave simulations or tailored method of moments (MoM)-solvers to access the radiation conductance by using formulas for the open end. It is shown that the radiation conductance is not a function of the gap geometry if the capacitive susceptance is small compared to the characteristic admittance of the line. The calculated radiation conductances for different capacitive gaps are compared to measurements of seven prototypes and MoM solutions.