A Wideband Transmission Line Model for a Slot Antenna

The traditional transmission line model for a slot antenna is typically only useful for the prediction of the first resonant mode. Here, a wideband transmission line model for a slot antenna is presented that describes the antenna's input impedance more accurately than previously published work, particularly at frequencies above the first resonant mode. To do this, we develop three improvements to the model: a modal equation that better approximates the frequency-dependent voltage distribution in the slot; an expression that captures more fully the inductive nature of the shorted ends of the slot; and a conductance-per-unit-length to predict the structure's loss characteristics. The results of this new wideband transmission line model are compared to commercial full-wave simulations and measurements for validation.