To evaluate the uncertainty caused by mismatch using Equivalent Capacitance Substitution Method (ECSM) with a T-network of matching resistors for monopole antenna calibration poses a problem. This paper derives the mathematical model of the mismatch factor through network analysis. The model can be used to evaluate the uncertainty component caused by mismatch or to calculate the mismatch correction factor using ECSM with a T-network for monopole antenna calibration. A case study on the application of the model to actual measurements is also included.
