I received several questions after the webinar 26-10-2023. One of them is where to put remote-electrode for Pole-dipole array?
I see three variants for remote electrode position.

1. Ideal remote electrode.  "When conducting a survey using the pole-dipole array, the transmitting remote electrode is moved to infinity. In other words, the transmitter remote electrode should be so far away from the receiver dipole that the instrument doesn’t sense the effect of the remote (pole) electrode, which is often 10 times the distance of the survey area." (www.agiusa.com)

2. Real remote electrode.
"10 times" is perfect but is not simple for real setup. For example, let's  consider 48 electrodes with 5 inter-electrode distance. AOmax~200m. It means that we need 2 km line for remote electrode. On the other hand, we can assume that an error of 5% is quite acceptable. In this case, we can place the electrode just 600 m perpendicular to the profile line.
3. Short remote electrode with apparent resistivity correction.
I - recommended area for remote electrode
II - acceptable area after apparent resistivity correction
III - invalid area for remote electrode
Apparent resistivity correction is recalculate apparent resistivity with geometric factor for 4 electrode array. It is possible by x2ipi software: Menu-Save-Remote electrode. Do not forget your GPS when you use Pole-dipole array!