We present a modeling technique to describe the behavior of an antenna with time-varying conductivity. The conducting channel of the antenna will consist of a series of individually-controlled plasma cells. This antenna will be fed with pulse-amplitude modulated signals. The pulses in these signals will travel down the length of the antenna but will be attenuated near the antenna tip. This time-domain matching technique allows for efficient matching at all frequencies. The time-varying antenna scheme is modeled using a modified version of Telegrapher's equations, which includes the effects of plasma dispersion. Theoretical plasma parameters are incorporated to develop requirements for plasma density and switching speed. Simulated results suggest that the time-varying antenna scheme will radiate more efficiently at low frequencies than existing electrically short antenna designs.