1D frequency-domain solutions are compared against Leroi ​http://www.amirainternational.com/WEB/site.asp?section=news&page=projectpages/p223f_software

Frequency-domain closed-loop source

Above, a comparison of Lemma with Leroi for a square closed-loop source transmitting 20 Amps at 50 kHz. Both solutions are in excellent agreement (left). The difference plot shows that the two codes fall within .1% throughout, with minor differences focused near the corners of the loop. Calculations were made at the air-earth interface.

Same as the above plots, but calculations were made at 20m depth.

In this plot, the horizontal components of the B field are shown at 20 m of depth.

In all of these cases Lemma is in excellent agreement with Leroi, the main differences can be seen in fairly low-order effects near the loop corners. This difference can be attributed to the fact that Lemma integrates around a current source, using horizontal electric dipoles (HED). Leroi and most other codes decompose the surface area of the loop and approximate the surface with vertical magnetic dipoles (VMD) . The VMD approach will therefore smooth out sharp corners. However, in reality, wires do not make perfectly sharp corners, and either approach is valid.