This article is a follow on from Receive only antenna for 160m – matching and performance discussion. It develops a SimNEC model that imports the loop impedance, and transforms it with an ideal transformer to quickly find an optimal transformer ratio and predict system losses.
Results are for the scenarios calculated and may not be extensible to different scenarios.
Another caveat: I have reservations about transmission line modelling in SimNEC, especially for composite conductors, but for the purposes of the discussion, assume that it is reasonably correct.
Above is the SimNEC model, it assumes reciprocity of the antenna system.
Whilst SimNEC may be able to run the NEC model internally, it uses an NEC-2 engine and I have used external NEC-4.2 which models small antennas more accurately.
The antenna is the one described at Receive only antenna for 160m – matching and performance discussion.
So, one can use the mouse wheel to dial the ideal transformer turns ratio D1.n up and down whilst observing T1.dBW (effectively -MismatchLoss), and choose the optimal turns ratio. for this 160m tuned Pennant, a turns ratio of 3 is optimal and MismatchLoss is just 0.018dB.