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.