Here is a picture story presented as 5 figures which hopefully will clear some questions. In the five figures we start with a circuit representation of a dipole which is a bit unusual as it has a resonant port Z of 500 ohms, pix_1. And it is set to achieve this at 7.1 MHz. If the VNA were connected to such an antenna the super VNA would demonstrate a S11 reflection plot contour vs. frequency on the Smith Chart shown in blue, see pix_2. For now, pay no attention to the plot in RED. We now add our simple L tuner shown in pix_3. And we connect our VNA to the 50 ohm match port and tune to achieve the best return loss possible. See pix_3, the tuner with antenna and pix_4, the return loss. We have achieved a return loss of over 40 dB. If we were to return this tuner network back to calculation what we would find is a conjugate S11 impedance profile that at a single frequency, namely 7.1 MHz that is exactly our antenna Z at this point, portrait of this Z is shown in RED in pix_2. Note it exactly crosses the antenna Z of 500 ohms. If the antenna Z at some other frequency point were complex, the same occurrence would occur. Again, at one specific frequency a real and complex point would occur synonymous with the tuner achieving best return loss at that single frequency. It is worthy to note, that if the tuner were allowed to be more complex, add more elements, that the trajectory of this plot shown in RED would match with higher fidelity over a broader range of frequencies. I hope this clarifies some of the points.
Alan
