Gap Discontinuity in Microstrip Lines: An Accurate Semianalytical Formulation

A semianalytical full-wave formulation is used to analyze a narrow gap in a microstrip line. The analysis assumes that the length of the gap is small compared to the strip width, but allows for an arbitrarily high frequency. The formulation accounts for radiation from the gap into space and into surface waves. Based on this formulation, the scattering parameters of the gap are obtained along with the complete equivalent circuit of the gap. The percentage of power lost due to gap radiation from an incident mode on the microstrip line is found, and the physics of the gap radiation are examined.