Small untuned loop for receiving – simple model with transformer gave a simple model for analysing a loop. If you haven’t already read it, you should. It provides a step towards understanding the YouLoop-2T at frequencies where is is a small loop (perimeter<λ/10).
Above is the Airspy Youloup-2T. Try to put the two turns thing out of your mind, it is misleading, panders to some common misunderstanding, and so does not help understanding.
This is somewhat similar to the simple loop, but now the transformer primary is connected to the loop gap terminals by two parallel sections of 50Ω transmission line, the combination being effectively a 100Ω with similar parameters to the component coax sections. Because of the series connection at the transformer and parallel connection at the loop gap, there is a 1:4 impedance transformation additional to that of the coax sections themselves. Continue reading Towards understanding the YouLoop-2T at MF/lowHF