A compact super low frequency receiving antenna in the form of a loop can be built for which the induced atmospheric noise voltage dominates both the antennas thermal noise voltage and preamplifier noise. Air-core and ferromagnetic-core ground loop receiving antennas were introduced, and mathematical calculation methods to analyse the ENF spectrum of the atmospheric noise and thermal noise were derived. The research identified the roles played by the various contributing factors such as antenna dimensions, wire conductivity, ferromagnetic-core permeability, etc. One air-core and three ferromagnetic-core antennas were designed, and a compromise core design was recommend, which takes advantage of the improvement that ferromagnetic cores can provide while largely avoiding the disadvantages.
Xie, Hui; Yang, Ming; and Ji, Long
"Mathematical Analysis of Super Low Frequency Ground Loop Receiving Antennas,"
Applied Mathematics & Information Sciences: Vol. 07:
3, Article 28.
Available at: https://digitalcommons.aaru.edu.jo/amis/vol07/iss3/28