Numerical calculations of RF efficiency from a soliton generating nonlinear transmission line

The output frequency and RF generating efficiency of a lumped element or periodic transmission line with nonlinear capacitors and linear inductors is investigated, using both a purely resistive linear load and a load that contains linear reactive components. The nonlinear transmission line creates high frequency RF by converting a long unipolar input pulse into a train of rapidly oscillating solitons. The RF efficiency increases as the modulation depth between adjacent solitons deepens, and is affected by the nonlinearity of the line and the total number of nonlinear stages used. A linear resistive termination distorts the pulse so as to reduce the RF efficiency, particularly when the nonlinearity is high. The RF efficiency is found to increase significantly when a linear load with reactive elements is used which absorbs the desired high frequency component of the signal but reflects the remaining low frequency parts of the signal back into the line.