Syntax for rectenna efficiency using Qucsstudio

I designed a voltage doubler rectenna using qucsstudio free simulation tool. Since it is a bit more manual than ADS (with equally amazing capabilities nonetheless), there is need for extra input on the data display in terms of syntax to give you the graph you need. I have obtained the S11 and S21 plots of the rectenna but am struggling with getting the conversion efficiency plot. Please note the circuit uses an AC voltage source with amplitude 'u_RF' along with a 50ohm R as power source, rest of the details are on the schematic and equations attached. I understand the rectenna conversion efficiency formula but need the correct way to put it in qucsstudio. Does anyone have an idea how it could be done please?