Rigorous Representation of a Shielded Three-Port Balun in the Simulation of an Antenna System

The use of a three-port shielded balun to drive an antenna allows a complete representation of the balun to be included in a numerical simulation of the antenna, including its nonidealities. The entire shielded feed configuration can be characterized by two coupled sources: a two- port Thevenin equivalent source. Here, such a model is derived using the generalized Thevenin's Theorem. This approach allows imbalance to be comprehensively represented in a numerical simulation of the antenna. It is a logical extension to and an improvement of the approach described in "Specification for radio frequency disturbance and immunity measurement apparatus and methods", where measured three-port balun data are used in conjunction with an analytical or numerical antenna model to predict site attenuation.