As a test, I built three loops of 500mm diameter, to dimensions as shown in the original Youloop drawing, but using 75 Ohm WF100 satellite TV coax consisting of a 1.00mm solid plain copper conductor, foam polyethylene dielectric, copper foil tape and a plain copper wire braid and a 1:1 transformer.
The loops were constructed as three different types, but as much as possible was kept the same in each loop.
- Moebius type similar to the Youloop design with a coax crossover at mid point
- Single turn screened loop with split in screen at centre point
- Single turn loop just using inner of coax with screen removed
The loops were energised with a 1m diameter square wire loop mounted "face to face" with the loop under test.
All loops were mounted in the same position in the near field and were predominantly flux coupled.
Varying the spacing between the loops from 0.3 to 2m produced similar results.
There are some lumps and bumps in the response curves as I measured the loops indoors, and although I attempted to minimise interaction with other nearby objects as much as possible, some is still present, although it was noticeable that the single turn screened loop with split in screen at centre point gave the most consistent results.
Note that these results depend upon the near field measurements being an accurate representation of what is also occurring in the far field, and this may not be the case.
The test set-up is shown below.