A symmetrical microstrip gap can be modeled by two open ends with a capacitive series coupling between the two ends. The physical layout is shown in fig. 11.6.
The equivalent -network of a microstrip gap is shown in figure 11.7. The values of the components are according to  and .
with and being the open end capacitances of a microstrip line (see eq. (11.192)). The numerical error of the capacitive admittances is less than mS for
The Y-parameters for the given equivalent small signal circuit can be written as stated in eq. (11.201) and are easy to convert to scattering parameters.