I'm continuously seeking a better LFMF receiving antennas. I've tried many different kinds but had not tried a simple loop lying on the ground, a LOG. I had been very skeptical of these but tried one anyway. The result, at least for me at my QTH, was very successful. Here is a note showing the details along with WSPR comparisons between antennas over different paths: Download 630m LOG notes. I'm not suggesting this is an antenna for everyone but as shown in the note it works great for me.