Ringing Effects Due to Non-ideal Components in Direct Antenna Modulation Transmitters

Direct antenna modulation (DAM) is a method used to transmit broadband signals through a narrowband antenna by switching the antenna or matching network at precise moments during the carrier cycle. In this paper, we study the effects of parasitics in the antenna and matching network and their effects on the DAM system. We demonstrate that parasitics introduce significant ringing after the switching instant that degrades the ability of DAM to store energy and effectively transmit broadband signals in practice. The parasitic effect is predicted by circuit model simulation and is validated with measurements with an equivalent antenna circuit model.