The YouLoop was first discussed in the airspy groups.io group in 2017, long before it became available commercially. I used 75 ohm RG59-Mini co-ax to construct mine and used a BN73-202 binocular core for the matching transformer. The original design used the smaller BN73-302 core with 5 turns per winding, so the commercial product probably uses something similar. I have two YouLoops, both inside our home. One is 5 feet by 3 feet and is around a window frame, hidden by the curtains. The other is in my roof-space and is of similar size to the commercial product. The large one assumes a rectangular shape when in use, while the one in the roof-space looks like an inverted triangle when suspended from the rafters. Both work well from LF ( I have received SAQ on 17.2kHz) to over 20 MHz and surprisingly well on the FM band and at around 215MHz, which is used for digital radio in the UK. For the 215MHz transmissions, which are vertically-polarised, the YouLoop functions better with the feed-point and crossover in the vertical sides of the rectangle. I can't adjust the one in the roof, but it works quite well as it is. Here in Southern England, the small one in the roof is capable of receiving US East Coast MW stations on my Airspy HF+, if conditions are right, although I do use a 30dB (adjustable) LNA as a feed of 16-metres of RG59-Mini has too much loss for the low- level signals from the YouLoop. I found that 12dB gain was sufficient on MW. The main advantages are good signal-to-noise performance, cheapness, easy construction, good performance indoors and useful from LF to VHF.